i have body built for around 4 years now, over the past 12 months started taking it more serious, stopped the alcohol/junk food, i have had massive gains on my whole body but i have really neglected my gut, it aint big its only 31inch which insnt bad for someone who is 6foot 5 and with a 44inch chest, but the problem is its still just sort of a pot belly, i have done little to no work on it ever and its really letting me down, because although i only have a pretty slim waist there is no defenition it still looks as though there is alot of fat there due to the lack of muscle, i have started doing the plank but with lifting my elbows off the floor so my upperbody is supported by my fists but im wanting to know some more exercises to help, i dont really want to do sit ups or anything "easyish" if you get what i mean because im not really bothered about developing my cardio fitness just the muscle.

cheers in advance for your help