Wife and husband scoff grain (5)
I believe the answer is:
wheat
'grain' is the definition.
(wheat is a kind of grain)
'wife and husband scoff' is the wordplay.
'wife' becomes 'w'.
'and' is a charade indicator (letters next to each other).
'husband' becomes 'h'.
'scoff' becomes 'eat' (I've seen this before).
'w'+'h'+'eat'='WHEAT'
(Other definitions for wheat that I've seen before include "(Pasta) cereal" , "A cereal, to be separated from chaff" , "Tall grass producing light brown grain" , "Cereal for bread/pasta" , "cereal's required" .)