Clerics are definitely the best for a mono-party comp, but it's hard to say "specialize in combat" better than fighter. It's been a long time, but from top of my head fighter gets: weapon specialization (for better or for worse), better HD/con hp adjustment, a better THAC0 table, the ablity to use any weapon which means longswords(!!!) and ranged weapons vs blunt weapons, and supplemented with some smart use of items and tactics you can go pretty far. From personal experience and as an example, you don't really need to cast fireball if you can get the conditions just right to form a dust explosion and pull out a lighter. Magic is just vastly simpler and easier with less hassle to get all the conditions right.
Course that's at the cost of the ability to heal wounds, the sheer utility spells bring, saves (lmao what is spell saves??), but if we're going with just a stand-up brawl, fighter is called fighter because it's good at fighting. It's not like clerics need to be better at fighting anyways nor should a mono-comp need to be looking at excellent, just good enough in all fields to do any job that a situation demands
And then paladins are basically the best of both worlds at the cost of high req. stats and a narrow code of conduct.
Bards in adnd iirc were a stat-locked class, hence why they are thief+. You had to roll well on your stats enough to even select the class.
