A bit of fluff in one's sherry (4)
I believe the answer is:
fino
'sherry' is the definition.
(I've seen this before)
'a bit of fluff in one's' is the wordplay.
'a bit of' says the answer is hidden in the clue.
'FINO' can be found hidden inside 'fluff in ones'.
(Other definitions for fino that I've seen before include "Type of sherry" , "Driest of the sherries" , "Dry Spanish sherry" , "Light-coloured sherry" , "Light dry sherry" .)