Types of bar in which to get drunk fast on empty stomach (6)
I believe the answer is:
shafts
'types of bar' is the definition.
'to get drunk fast on empty stomach' is the wordplay.
'to get drunk' is an anagram indicator.
'on' says to put letters next to each other.
'empty' means to remove the middle letters.
'stomach' with its middle removed is 'sh'.
'fast' with letters rearranged gives 'afts'.
'afts' put after 'sh' is 'SHAFTS'.
'in which' acts as a link.
(Other definitions for shafts that I've seen before include "Arrows and rays of light" , "Columns, of light say" , "Screws" , "Arrows or mine tunnels" , "Arrows or mine passages" .)