Spireites teenager Conor Townsend, on loan from Hull, was shown a straight red when he caught Will Haining with an elbow in the 64th minute.
It came after Townsend had scored his first league goal with a super free-kick to cancel out Chris McCready's headed opener.
"I think it was a fair result," Bentley said. "When any team goes down to 10 men and you've got 11 you fancy your chances, but fair play to them, they kept coming at us.
"It was an eventful game that was swinging both ways but I'm a little bit disappointed we didn't show enough desire to win the game when we had all our fresh legs on and pace up front.
"But you're not always going to play well and particularly at this stage of the year with a lot of games when we are stretched for bodies, sometimes it takes its toll on people."
- Sports & Recreation
- Will Haining