First of all, when you call and do make your flush it is likely you get paid off since he'll expect that most flush draws have nice combos with them that would 3-bet the flop so he's not going to be snapfolding a set/twopair or JJ or something. Your pair outs are also potentially live and folding just seems too weak and 3-betting seems marginally worse than calling since you're not getting called by worse much and there's not a ton to win yet. Calling and c/shoving any decent turn (any club/7,9,Q) seems alright since at least then you profit most vs his air range. And people sometimes give up after bluff raising flop so you can take down the river with a 2/3 pot bet when you miss repping overpairs that would take the same line.