Fill beaker coy drunk holds (6)
I believe the answer is:
occupy
'fill' is the definition.
(I know that fill can be written as occupy)
'beaker coy drunk holds' is the wordplay.
'beaker' becomes 'cup' (I've seen this before).
'drunk' indicates an anagram.
'holds' means one lot of letters goes inside another.
'coy' anagrammed gives 'ocy'.
'cup' put within 'ocy' is 'OCCUPY'.
(Other definitions for occupy that I've seen before include "'Fill a position, reside (6)'" , "People" , "Be present in" , "Bring engagement" , "Employ" .)