Sentimental character from Olympus retiring (5)
I believe the answer is:
mushy
'sentimental' is the definition.
('mushy' can be a synonym of 'sentimental')
'character from olympus retiring' is the wordplay.
'character from olympus' becomes 'mu' (Greek letter).
'retiring' becomes 'shy' (I've seen this in other clues).
'mu'+'shy'='MUSHY'
(Other definitions for mushy that I've seen before include "Gushing" , "Insincerely emotional" , "Sentimental; type of peas" , "-- peas, with fish and chips" , "Mawkish" .)