A vet upset with service in pub (6)
I believe the answer is:
tavern
'pub' is the definition.
(thesaurus)
'a vet upset with service' is the wordplay.
'upset' indicates an anagram.
'with' says to put letters next to each other.
'service' becomes 'rn' (abbreviation for Royal Navy).
'a'+'vet'='avet'
'avet' with letters rearranged gives 'tave'.
'tave'+'rn'='TAVERN'
'in' is the link.
(Other definitions for tavern that I've seen before include "An old inn or hostelry" , "Tap house" , "An old inn, musically in the town" , "Local" , "Tap-house" .)