Stewed apricot not right with a pudding (7)
I believe the answer is:
tapioca
'pudding' is the definition.
(tapioca pudding is a kind of pudding)
'stewed apricot not right with a' is the wordplay.
'stewed' indicates an anagram.
'not' suggests deleting specific letters.
'right' becomes 'r' (abbreviation).
'with' is an insertion indicator.
'apricot' with 'r' removed is 'apicot'.
'apicot' is an anagram of 'tpioca'.
'tpioca' placed around 'a' is 'TAPIOCA'.
(Other definitions for tapioca that I've seen before include "it thickens" , "Starch from cassava used in making puddings" , "Ciao, Pat, have some strange pudding" , "Foodstuff used as a thickener" , "Pudding maker" .)