Punishment for most of this cake being spongy, right? (5,3)
I believe the answer is:
thick ear
'punishment' is the definition.
'most of this cake being spongy right?' is the wordplay.
'most of' means to remove the last letter.
'being spongy' indicates an anagram (spongy can mean malleable or yielding).
'right?' becomes 'r' (common abbreviation).
'this' with its final letter removed is 'thi'.
'cake' is an anagram of 'ckea'.
'thi'+'ckea'+'r'='THICK EAR'
'for' is the link.
(Other definitions for thick ear that I've seen before include "not fine musical appreciation" , "head injury" , "Sign of punishment" .)