400NL AT top pair reraised pot against a minraise from unknown

[Vinetou]

PokerStars No-Limit Hold'em, $4 BB (2 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Hero ($532.55)
Button ($470.50)

Preflop: Hero is BB with A[img]/images/graemlins/heart.gif[/img], T[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">Button raises to $12</font>, <font color="#CC3333">Hero raises to $40</font>, Button calls $28.

Flop: ($80) 4[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $56</font>, <font color="#CC3333">Button raises to $112</font>,

I didn't play a lot of hands with villain, but he probably views me as aggressive. One hand I checkraised flop and then c/f turn. So he is pretty much unknown. Reraising preflop with ATo is my default play, some people might disagree with that. However, I don't know what his minraise on the flop means. Would he playback at me with a flush draw on an ace high board after I reraise and make a c bet? The only hands I am really worried about is AQ (maybe, he might 4 bet me with that?)AJ, A8, or A4.

I think this is a push or fold decision. I have a tough time folding top pair in HU, because most of the time it is good. So what do you do here?