Guzzler emptied vermouth bottle (4)
I believe the answer is:
grit
'bottle' is the definition.
(I've seen this before)
'guzzler emptied vermouth' is the wordplay.
'emptied' suggests removing the centre.
'vermouth' becomes 'it' (short for 'Italian vermouth' as in 'gin and it').
'guzzler' with its centre removed is 'gr'.
'gr'+'it'='GRIT'
(Other definitions for grit that I've seen before include "Small hard particles - courage" , "Gravel or colloquial courage" , "Courage - clench - small particle of stone" , "Pluck; sand particles" , "Fortitude" .)