Sinners lost outside pub (3)
I believe the answer is:
inn
'pub' is the definition.
(thesaurus)
'sinners lost outside' is the wordplay.
'outside' says the answer is hidden in the clue (a word is around or outside the answer).
'INN' is hidden in the letters of 'sinners lost'.
(Other definitions for inn that I've seen before include "Roadhouse" , "pubs?" , "Swiss river" , "watering hole" , "Resting place" .)