Restricted cover about an unusual item (7)
I believe the answer is:
limited
'restricted' is the definition.
(similar in meaning)
'cover about an unusual item' is the wordplay.
'cover' becomes 'lid' (lid is a kind of cover).
'about' means one lot of letters goes inside another.
'an unusual' is an anagram indicator.
'item' anagrammed gives 'mite'.
'lid' placed around 'mite' is 'LIMITED'.
(Other definitions for limited that I've seen before include "was restricting" , "Of small range" , "short of talent" , "Sort of company" , "Bound" .)