Birmingham City have doubled their total of summer acquisitions to six by completing three signings in one day.
Dundee United defender Gavin Gunning, 23, has signed a pre-contract agreement to become a Blues player on a one-year deal on 1 July.
Utility man David Edgar, 27, has arrived after being let go by Burnley.
Blues have also re-signed striker Wes Thomas, also 27, who helped to fire Rotherham United to promotion from League One a month ago.
Thomas, plucked from non-league football by Dagenham & Redbridge in 2008, has since played in the Football League for Cheltenham Town, Crawley Town, Bournemouth, Portsmouth, Blackpool and Blues, before spending the second half of last season at Rotherham.
His six goals for the Millers on a short-term contract, taking his career haul of league goals to within one of his half-century, helped Rotherham to win promotion to the Championship.
"He had a great end to last season and played a huge part in getting Rotherham promoted," said Clark. "I know they wanted to keep him.
"Wes gives us power and, alongside Matt Green, we've got two strikers with really good pace.
"That, coupled with Lee Novak, and hopefully one other striker of a different type, will give us options at the top end of the pitch."
Thomas returns to St Andrew's on a two-year contract to rejoin Clark, who was pleased with his efforts when he scored three goals in 11 games on loan from Bournemouth at the back end of the 2012-13 season.
"I was really happy with him when he was here before," said Clark. "When he left Bournemouth they were asking for a loan fee which we couldn't do at the time because of financial constraints."
Clark has also worked before with Edgar, who has also signed a two-year deal, having been his reserve-team boss at Newcastle.
"His versatility is important to us. He can play in three positions," said Clark.
"He started out as a right-sided centre-half, but broke into the Newcastle first team as a right-back and played the majority of his games there, where he actually scored his first goal, against Manchester United.
"He then decided it was time to move on and went to Burnley and has played a lot of his games - certainly last season - as a defensive central midfield player.
"He's competitive in the air and aggressive. He sees himself more as a central midfield player, but he's comfortable in all of them."
Edgar has made 114 appearances since leaving Newcastle to join the Clarets for their last spell in the top flight in 2009-10, but last season he made just five starts, being largely restricted to a substitute's role.
Dublin-born former Republic of Ireland Under-21 international Gunning was on Blackburn Rovers' books, spending loan spells with Tranmere Rovers, Rotherham United, Bury and Motherwell.
Since moving north of the border three years ago, he has scored 10 times in 99 games.
Having escaped relegation on a dramatic final day of the Championship season, Blues remain up for sale.
But, while Clark knows that circumstances may change should any new owners come in, he is still operating as per normal by beginning the reconstruction of his squad.
Six players - Wade Elliott, Peter Lovenkrands, Hayden Mullins, Brian Howard, Aaron Martin and Darren Ambrose - were released at the end of the season.
And, with Clark having confirmed that out-of-contract duo Nikola Zigic and Chris Burke will be on their way, along with the return of loan players Federico Macheda, Emyr Huws and Jordan Ibe to their parent clubs, there are holes to fill.
But the arrival of Gunning, Edgar and Thomas, the third Blues signing to arrive from a League One club, further bolsters Clark's squad.