A vet disturbed by service in bar (6)
I believe the answer is:
tavern
'bar' is the definition.
(thesaurus)
'a vet disturbed by service' is the wordplay.
'disturbed' indicates anagramming the letters.
'by' means one lot of letters go next to another.
'service' becomes 'rn' (abbreviation for Royal Navy).
'a'+'vet'='avet'
'avet' anagrammed gives 'tave'.
'tave'+'rn'='TAVERN'
'in' is the link.
(Other definitions for tavern that I've seen before include "Tap house" , "Old-fashioned word for pub" , "Building with a bar" , "An old inn or hostelry" , "Alehouse" .)