A hard beret, carelessly worn (10)
I believe the answer is:
threadbare
'worn' is the definition.
(similar in meaning)
'a hard beret carelessly' is the wordplay.
'carelessly' indicates an anagram.
'a'+'hard'+'beret'='ahardberet'
'ahardberet' with letters rearranged gives 'THREADBARE'.
(Other definitions for threadbare that I've seen before include "Shabby" , "Hackneyed" , "cliche-ridden" , "Ragged" , "deprived of nap" .)