Sort out hostelry? I’m amazed about that (6)
I believe the answer is:
winnow
'sort out' is the definition.
(thesaurus)
'hostelry? i'm amazed about that' is the wordplay.
'hostelry?' becomes 'inn' ('inn' can be a synonym of 'hostelry').
'i'm amazed' becomes 'wow'.
'about that' means one lot of letters goes inside another.
'inn' put within 'wow' is 'WINNOW'.
(Other definitions for winnow that I've seen before include "Dehusk grain using air currents" , "Separate the wheat from the chaff" , "Sift out" , "Separate chaff from grain" , "Blow air through (grain) to remove chaff" .)