looks like a 7 or a bluff to me. i kinda think hes bluffing here more than 15-25%. he could have easily picked up a draw on the turn and C/Red it then decided he was going to try to continue the bluff after he missed. I just think there are more hands that he could have that contain like a flush draw then hands with 7s. because hes not calling preflop with too many hands with a 7 in them is he? but i guess he isnt guranteed to play a draw like this either. overall i think you are getting good enough odds for this to be a profitable call but it does seem kinda close.