Not accustomed to us appearing in the nude, perhaps (6)
I believe the answer is:
unused
'not accustomed to' is the definition.
(I've seen this before)
'us appearing in the nude perhaps' is the wordplay.
'appearing in' is an insertion indicator.
'perhaps' indicates an anagram.
'nude' is an anagram of 'uned'.
'us' inserted into 'uned' is 'UNUSED'.
(Other definitions for unused that I've seen before include "In mint condition" , "Extra" , "Surplus" , "'Fresh, new (6)'" , "idle" .)