The fruit of sterile monasticism? (5)
I believe the answer is:
lemon
'the fruit' is the definition.
(lemon is a kind of fruit)
'of sterile monasticism?' is the wordplay.
'of' indicates a hidden word.
'LEMON' is hidden in the letters of 'sterile monasticism'.
(Other definitions for lemon that I've seen before include "Tone" , "very different from peach?" , "Yellow fruit (it's also the answer!)" , "Leaving body" , "failure" .)