Emblem right for nocturnal mammal (6)
I believe the answer is:
badger
'nocturnal mammal' is the definition.
(I've seen this before)
'emblem right' is the wordplay.
'emblem' becomes 'badge' (badge is a kind of emblem).
'right' becomes 'r' (common abbreviation).
'badge'+'r'='BADGER'
'for' is the link.
(Other definitions for badger that I've seen before include "Pester the burrowing animal" , "Mammal, striped head" , "Harass, pester" , "Countryside mammal" , "Disturb" .)