Merit new headdress (5)
I believe the answer is:
mitre
'headdress' is the definition.
(I know that mitre is a type of headdress)
'merit new' is the wordplay.
'new' is an anagram indicator.
'merit' anagrammed gives 'MITRE'.
(Other definitions for mitre that I've seen before include "top?" , "episcopal head may come under this" , "Corner joint - bishop's headdress" , "Sort of joint" , "Type of joint - bishop's hat" .)