Sentimental Greek character disinclined to speak (5)
I believe the answer is:
mushy
'sentimental' is the definition.
(I know that sentimental can be written as mushy)
'greek character disinclined to speak' is the wordplay.
'greek character' becomes 'mu' (letter from the Greek alphabet).
'disinclined to speak' becomes 'shy' (I am not sure about this - if you are sure you should believe this answer much more).
'mu'+'shy'='MUSHY'
Can you help me to learn more?
(Other definitions for mushy that I've seen before include "Gushing" , "Insincerely emotional" , "-- peas, with fish and chips" , "Mawkish" , "Sentimental; type of peas" .)