Item one found in poor claret (7)
I believe the answer is:
article
'item' is the definition.
(I've seen this in another clue)
'one found in poor claret' is the wordplay.
'one' becomes 'I' (Roman numeral).
'found in' indicates putting letters inside.
'poor' indicates an anagram.
'claret' with letters rearranged gives 'artcle'.
'i' inserted within 'artcle' is 'ARTICLE'.
(Other definitions for article that I've seen before include "Newspaper feature or a separate thing" , "Possibly the" , "Recital (anag.)" , "thing required" , "Newspaper piece" .)