Concentrated artillery bombardment (7)
I believe the answer is:
barrage
'concentrated artillery bombardment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for barrage that I've seen before include "Continuous artillery fire" , "a lot of shells" , "flood protection" , "Continuous fusillade or a torrent of questions" , "Artillery bombardment; barrier across a river" .)