Swathe of attacks coming through river (7)
I believe the answer is:
expanse
'swathe' is the definition.
(I've seen this before)
'attacks coming through river' is the wordplay.
'attacks' becomes 'pans' (pan can mean to attack or criticise).
'coming through' means one lot of letters goes inside another.
'river' becomes 'exe' (River Exe).
'pans' inserted inside 'exe' is 'EXPANSE'.
'of' acts as a link.
(Other definitions for expanse that I've seen before include "Stretch - extent" , "Swathe" , "Wide continuous area" , "reach" , "Wide area of open land or space" .)