WordNet (r) 3.0 (2006):

neaten
    v 1: put (things or places) in order; "Tidy up your room!" [syn:
         tidy, tidy up, clean up, neaten, straighten,
         straighten out, square away]
    2: care for one's external appearance; "He is always well-
       groomed" [syn: groom, neaten]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "neaten":
   clean up, clear the decks, clear up, fix up, groom, police,
   police up, put in order, put in trim, spruce, spruce up,
   straighten out, straighten up, tidy, tidy up, trig, trig up, trim,
   trim up