Seizes third bourbon and slurps litre away (6)
I believe the answer is:
usurps
'seizes' is the definition.
(I've seen this in another clue)
'third bourbon and slurps litre away' is the wordplay.
'third bourbon' becomes 'u' (3rd letter of 'bourbon').
'and' means one lot of letters go next to another.
'litre' becomes 'L' (abbreviation).
'away' suggests deleting specific letters.
'slurps' with 'l' taken out is 'surps'.
'u'+'surps'='USURPS'
(Other definitions for usurps that I've seen before include "takes place" , "Seizes (illegally)" , "Takes a position of power illegally" , "Takes power wrongfully, wrests" , "Seizes wrongfully or by force" .)