Bottle: guzzler emptied it (4)
I believe the answer is:
grit
'bottle' is the definition.
(I've seen this before)
'guzzler emptied it' is the wordplay.
'emptied' means to remove the middle letters.
'guzzler' with its centre removed is 'gr'.
'gr'+'it'='GRIT'
(Other definitions for grit that I've seen before include "Courage, small stones" , "Coarse stone or sand" , "lamb" , "Grains of rock or sand" , "Fortitude" .)