Fruit trees or greens (7)
I believe the answer is:
orchard
'fruit trees' is the definition.
(I've seen this before)
'or greens' is the wordplay.
'greens' becomes 'chard' (chard is a kind of greens).
'or'+'chard'='ORCHARD'
(Other definitions for orchard that I've seen before include "Enormous" , "Enclosure containing fruit trees" , "Trees bearing apples perhaps" , "Field of fruit trees" , "Fruit tree plantation" .)