Piece of blancmange (3)
I believe the answer is:
man
'piece' is the definition.
('man' can be a synonym of 'piece')
'of blancmange' is the wordplay.
'of' indicates the answer is hidden within the clue.
'MAN' is hidden within 'blancmange'.
(Other definitions for man that I've seen before include "race" , "Vassal; chess piece" , "Valet" , "Dude" , "Geezer" .)