A9s flops combo draw

[DanJ.]

villain is 25/15/3 over 1.5k sample, he likes to 3bet me a lot, doesnt raise me on the flop a lot but he has, we dont usually tangle in big pots like this.

Hero $250
villain covers

4 handed
villain raises to $6, btn folds, sb folds, Hero calls $6 with A [img]/images/graemlins/club.gif[/img]9 [img]/images/graemlins/club.gif[/img]

flop - 3 [img]/images/graemlins/club.gif[/img]4 [img]/images/graemlins/club.gif[/img]5 [img]/images/graemlins/diamond.gif[/img]
Hero bets $8, villain raises to $21, hero pushes???