Fill drinking vessel coy drunk holds (6)
I believe the answer is:
occupy
'fill' is the definition.
(I know that fill can be written as occupy)
'drinking vessel coy drunk holds' is the wordplay.
'drinking vessel' becomes 'cup' (I've seen this in another clue).
'drunk' indicates an anagram.
'holds' indicates putting letters inside.
'coy' anagrammed gives 'ocy'.
'cup' placed within 'ocy' is 'OCCUPY'.
(Other definitions for occupy that I've seen before include "Hold; tenant" , "Take up (time or space)" , "Bring engagement" , "Busy - tenant" , "Be present in" .)