Old man stewing fruit, usually known by another name (6)
I believe the answer is:
almond
'fruit usually known by another name' is the definition.
(fruit that would more commonly be called a nut)
'old man stewing' is the wordplay.
'stewing' indicates an anagram.
'old'+'man'='oldman'
'oldman' anagrammed gives 'ALMOND'.
(Other definitions for almond that I've seen before include "Nut-like kernel" , "one of the nuts" , "Fruit for marzipan" , "Yellowish brown" , "Edible nut" .)