Fruit worker in grassland (8)
I believe the answer is:
plantain
'fruit' is the definition.
(I've seen this before)
'worker in grassland' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'in' indicates putting letters inside.
'grassland' becomes 'plain' (I have seen 'Open grassland' mean 'plain' so perhaps 'grassland' could also mean 'plain').
'ant' put into 'plain' is 'PLANTAIN'.
(Other definitions for plantain that I've seen before include "Sort of banana" , "Large banana - weed" , "Low-growing plant; type of banana" , "Cooking banana" , "Tropical plant like a banana" .)