Not all appreciated a mouldy cheese (4)
I believe the answer is:
edam
'cheese' is the definition.
(I've seen this before)
'not all appreciated a mouldy' is the wordplay.
'not all' indicates the answer is hidden within the clue.
'EDAM' can be found hidden inside 'appreciated a mouldy'.
(Other definitions for edam that I've seen before include "Netherlands cheese" , "Type of cheese" , "Madeinto popular cheese" , "Round, yellow cheese" , "Dairy product" .)