Compensation for barrier takes a long time (7)
I believe the answer is:
damages
'compensation' is the definition.
(damages is a kind of compensation)
'barrier takes a long time' is the wordplay.
'barrier' becomes 'dam' (dam is a kind of barrier).
'takes' is a charade indicator (letters next to each other).
'a long time' becomes 'ages' (ages can mean a very long time).
'dam'+'ages'='DAMAGES'
'for' acts as a link.
(Other definitions for damages that I've seen before include "Moneys paid as compensation for an injury" , "Hurts" , "Money awarded as compensation" , "Harms" , "Money paid in compensation for loss or injury" .)