In pubs, one cheers brewer (7)
I believe the answer is:
barista
'brewer' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'in pubs one cheers' is the wordplay.
'in' indicates putting letters inside.
'pubs' becomes 'bars' (a bar is a pub).
'one' becomes 'i' (Roman numeral).
'cheers' becomes 'ta' (both can informally mean thank you).
'bars' enclosing 'i' is 'baris'.
'baris'+'ta'='BARISTA'
Can you help me to learn more?
(Other definitions for barista that I've seen before include "coffee-maker" , "Coffee bar server" , "Coffee servitor" , "Coffee maker?" , "Coffee bar worker" .)