[allenciox]

You HAVE to call. Following are his possible hands:
1. 5-10% stone cold bluff. You are almost 100% here.
2. Hands which you beat, on average, about 2/3 of the time --- Ax clubs --- he might limp with any ace-suited, a lot of people do (11 hands, excluding AQclubs which beats you). AJo or ATo with an ace of clubs (6 hands), in which case he has a backdoor nut flush draw, a gutshot straight draw, and probable outs pairing the board or the ace in his hand. KQo (12 hands). Perhaps even QJo or QTo, particularly if one of the cards is a club (24 hands). JTo (9 hands) Total of 72 hands. He doesn't have QQ-AA, as he would have almost certainly raised with those to isolate the limper in front of him.

3. Hands which currently have you beat, but you can outdraw --- these include AQo(16 hands) you have 4 outs in this case which will hit 1/6 of the time. Also KJ (9 hands), and possibly TT (3 hands) (JJ probably would have raised as well, and TT might, so we'll just count one of them). Total of 28 hands.

Even if we completely discount the possibility he is bluffing, we have 72 hands that we have a 67% edge and 28 hands that we are averaging only about 15%. We have better than a 52% equity in the pot, but it is paying us almost 2:1 for us to call the bet! Even if we say he might not have raised all-in with some of those 72 hands, it is a trivial call.