Slot-machine fruit (5)
I believe the answer is:
'slot-machine fruit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lemon that I've seen before include "Tone" , "Melon (anag)" , "Citrus fruit (is it the answer?)" , "Small evergreen fruit tree" , "Useless object" .)