Emptied brandy with lager when drunk, as a rule (2,3,5)
I believe the answer is:
by and large
'as a rule' is the definition.
(I've seen this before)
'emptied brandy with lager when drunk' is the wordplay.
'emptied' suggests removing the centre.
'with' becomes 'and' (I've seen this before**).
'when drunk' indicates anagramming the letters (I've seen this in other clues).
'brandy' with its centre taken out is 'by'.
'lager' with letters rearranged gives 'large'.
'by'+'and'+'large'='BY AND LARGE'
(Other definitions for by and large that I've seen before include "As a rule" , "Speaking generally" , "for the most part" , "On the whole" , "In general" .)