Saw person wandering in empty pub (7)
I believe the answer is:
proverb
'saw' is the definition.
(synonyms)
'person wandering in empty pub' is the wordplay.
'person wandering' becomes 'rover' (someone who roves around).
'in' indicates putting letters inside.
'empty' suggests removing the centre.
'pub' with its centre removed is 'pb'.
'rover' put within 'pb' is 'PROVERB'.
(Other definitions for proverb that I've seen before include "Old saw" , "Short saying expressing a supposed truth" , "OT saying" , "Aphorism" , "Old saying, perhaps by Solomon?" .)