Fruit a necessity, as on the counter (7)
I believe the answer is:
satsuma
'fruit' is the definition.
(I know that satsuma is a type of fruit)
'a necessity as on the counter' is the wordplay.
'necessity' becomes 'must' (I've seen this before).
'on the counter' says the letters should be written in reverse (counter can mean in the opposite direction).
'a'+'must'+'as'='amustas'
'amustas' reversed gives 'SATSUMA'.
(Other definitions for satsuma that I've seen before include "healthy snack" , "Loose-skinned tangerine" , "A small citrus fruit" , "that is easily uncovered" , "Citrus fruit from Japan" .)