Fruit boy found behind barrier (6)
I believe the answer is:
damson
'fruit' is the definition.
(I know that damson is a type of plum)
'boy found behind barrier' is the wordplay.
'boy' becomes 'son' (synonyms).
'found behind' is a charade indicator (letters next to each other) (some letters go behind others).
'barrier' becomes 'dam' (dam is a kind of barrier).
'son' after 'dam' is 'DAMSON'.
(Other definitions for damson that I've seen before include "Sort of plum" , "Plum-coloured" , "Small fruit for nomads" , "Small dark-purple plum" , "fruit tree" .)