Nude boxing - tabloid onslaught! (7)
I believe the answer is:
barrage
'onslaught' is the definition.
(barrage is a kind of onslaught)
'nude boxing tabloid' is the wordplay.
'nude' becomes 'bare' (I've seen this before).
'boxing' indicates putting letters inside ('box' can mean contain, as in to put in a box).
'tabloid' becomes 'rag' ('rag' can be a synonym of 'tabloid').
'bare' placed around 'rag' is 'BARRAGE'.
(Other definitions for barrage that I've seen before include "Artillery bombardment; barrier across a river" , "Concentrated artillery bombardment" , "Artillery bombardment; flood barrier" , "Sustained fire" , "Continuous fusillade or a torrent of questions" .)