Reserves on booze reportedly! (8)
I believe the answer is:
resource
'reserves' is the definition.
(thesaurus)
'on booze reportedly' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'booze' becomes 'sauce' (both can informally mean alcohol).
'reportedly' shows a homophone (sound like).
'sauce' is a homophone of 'source'.
're'+'source'='RESOURCE'
(Other definitions for resource that I've seen before include "Stock of something to draw upon" , "A supply of materials" , "Facility" , "From which help can be obtained" , "Source of help" .)