New remit for headwear (5)
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for nitre that I've seen before include "explosive ingredient" , "Chemical" , "Otherwise saltpetre" , "what goes into bangers" , "Mineral used in gunpowder" .)
'for headwear' is the definition.
(headwear worn by a bishop)
'new remit' is the wordplay.
'new' is an anagram indicator.
'remit' is an anagram of 'MITRE'.
(Other definitions for mitre that I've seen before include "Timer for a bishop." , "Remit (anag.)" , "Item of headgear" , "in which one might find a bishop" , "A bishop's tall hat" .)