Continuous fire from gunners aboard boat (7)
I believe the answer is:
barrage
'continuous fire' is the definition.
(I've seen this before)
'gunners aboard boat' is the wordplay.
'gunners' becomes 'RA' (Royal Artillery).
'aboard' indicates putting letters inside.
'boat' becomes 'barge' (barge is a kind of boat).
'ra' inserted into 'barge' is 'BARRAGE'.
'from' is the link.
(Other definitions for barrage that I've seen before include "Sustained attack - means of damming river" , "Heavy, continuous fire" , "Artillery bombardment; barrier across a river" , "flood protection" , "Heavy artillery fire" .)