Fleshy soft mass (5)
I believe the answer is:
plump
'fleshy' is the definition.
(thesaurus)
'soft mass' is the wordplay.
'soft' becomes 'p' (musical abbreviation for 'piano').
'mass' becomes 'lump' (I have seen 'Shapeless mass' mean 'lump' so perhaps 'mass' could also mean 'lump'**).
'p'+'lump'='PLUMP'
(Other definitions for plump that I've seen before include "Corpulent" , "stout" , "Chubby, fat" , "Rotund" , "Well-rounded" .)