A contrary stance for moralist (5)
I believe the answer is:
aesop
'moralist' is the definition.
(I've seen this in another clue)
'a contrary stance' is the wordplay.
'contrary' says the letters should be written in reverse.
'stance' becomes 'pose' (I've seen this in another clue).
'pose' reversed gives 'esop'.
'a'+'esop'='AESOP'
'for' is the link.
(Other definitions for aesop that I've seen before include "fabulous figure?" , "his writings were fabulous" , "A pose by Greek writer of fables" , "Great Greek teller of animal fables" , "Greek author, famous for his fables" .)