Tidy, maintained without muck for a start (5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

M[uck] in KEPT [maintained] I think I’ve only seen this word in its negative form, unkempt: Colliins says it’s a 20th century  back formation – but also says it’s from the dialect [Chambers says Old English] ‘kemb’, to comb