Man, perhaps, is allowed to scratch tail (4)
I believe the answer is:
isle
'man perhaps' is the definition.
(I've seen this before)
'is allowed to scratch tail' is the wordplay.
'allowed' becomes 'let' (I've seen this before).
'to scratch tail' means to remove the last letter.
'let' with its last letter taken off is 'le'.
'is'+'le'='ISLE'
(Other definitions for isle that I've seen before include "The Lake ... of Innisfree (W.B.Yeats)" , "somewhere surrounded by water" , "what Donne implied he wasn't" , "-- of Ely, Dogs, Man" , "-- of Dogs, area of London" .)