Huddersfield, in losing their first League One match since December, were second-best throughout in Tuesday night's League One encounter at St Mary's and could not live with the home side's thrilling attacking football.
Clark said: "From 10 minutes on there was only one team that was going to win - it was men against boys.
"I could have substituted all 10 outfield players at half-time and after the break it was about damage limitation.
"I hate losing but sometimes you can accept it however I cannot accept that. I can only apologise to the fans because that was not worthy of their support. How we respond to that will tell me a lot about the players. It will tell me if they are young men or boys."