Smashed cartel retains one item (7)
I believe the answer is:
article
'item' is the definition.
(I've seen this before)
'smashed cartel retains one' is the wordplay.
'smashed' is an anagram indicator.
'retains' indicates putting letters inside.
'one' becomes 'I' (Roman numeral).
'cartel' is an anagram of 'artcle'.
'artcle' going around 'i' is 'ARTICLE'.
(Other definitions for article that I've seen before include "Possibly the" , "Newspaper feature or a separate thing" , "News story" , "A rewritten piece" , "Newspaper essay" .)