Fruit found in Jerusalem once (5)
I believe the answer is:
lemon
'fruit' is the definition.
(lemon is a kind of fruit)
'in jerusalem once' is the wordplay.
'in' says the answer is hidden in the clue.
'LEMON' can be found hidden inside 'jerusalem once'.
'found' is the link.
(Other definitions for lemon that I've seen before include "Yellow citrus fruit with acid taste" , "Feeble thing (colloq.); fruit tree" , "something unattractive" , "Fruit - useless thing" , "Useless object" .)