Barriers no problem for plum (6)
I believe the answer is:
damson
'plum' is the definition.
(damson plum is a kind of plum)
'barriers no problem' is the wordplay.
'barriers' becomes 'dams' (dam is a kind of barrier).
'problem' indicates anagramming the letters.
'no' with letters rearranged gives 'on'.
'dams'+'on'='DAMSON'
'for' is the link.
(Other definitions for damson that I've seen before include "jam producer" , "Acid purple plum" , "Nomads (anag)" , "Small tart plum" , "Kind of plum for nomads" .)