Doubtfully ate up mostly foul stew (3-2-3)

I believe the answer is:

pot-au-feu

'stew' is the definition.
(pot-au-feu is a kind of stew)

'doubtfully ate up mostly foul' is the wordplay.
'doubtfully' indicates an anagram.
'mostly' means to remove the last letter.
'foul' with its last letter taken away is 'fou'.
'ate'+'up'+'fou'='ateupfou'
'ateupfou' is an anagram of 'POT-AU-FEU'.

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app