Memo returned about Liberal man (5)
I believe the answer is:
elton
'man' is the definition.
'memo returned about liberal' is the wordplay.
'memo' becomes 'note' (I've seen this in another clue).
'returned' is a reversal indicator.
'about' is an insertion indicator.
'liberal' becomes 'l' (abbreviation).
'note' written backwards gives 'eton'.
'eton' placed around 'l' is 'ELTON'.
(Other definitions for elton that I've seen before include ". . . . . John (musician)" , "One John" , "Sir ___ John, singer-songwriter" , "Sir - - John, singer songwriter" , "Let on he's John, the singer" .)