Hit barrier at work (6)
I believe the answer is:
wallop
'hit' is the definition.
(walloping is a kind of hitting)
'barrier at work' is the wordplay.
'barrier' becomes 'wall' (I've seen this before).
'at' says to put letters next to each other.
'work' becomes 'op' (abbreviation for opus).
'wall'+'op'='WALLOP'
(Other definitions for wallop that I've seen before include "Strike very hard" , "Thump" , "Punch" , "big hit" , "batter" .)