Lout of a sort (3)
I believe the answer is:
oaf
'lout' is the definition.
(I know that lout can be written as oaf)
'of a sort' is the wordplay.
'sort' indicates anagramming the letters.
'of'+'a'='ofa'
'ofa' with letters rearranged gives 'OAF'.
(Other definitions for oaf that I've seen before include "buffoon" , "Goon" , "Idiot" , "Lout, lummox" , "Stupid lout" .)