Beast seen in mist again (4)
I believe the answer is:
stag
'beast' is the definition.
(I know that stag is a type of buck)
'in mist again' is the wordplay.
'in' indicates the answer is hidden within the clue.
'STAG' is hidden in the letters of 'mist again'.
'seen' is the link.
(Other definitions for stag that I've seen before include "Without women" , "Deer; with only men" , "Unaccompanied man at party" , "Excluding women" , "No women allowed" .)