Cheering custom following papal trip (8)
I believe the answer is:
applause
'cheering' is the definition.
(thesaurus)
'custom following papal trip' is the wordplay.
'custom' becomes 'use' (use is a kind of custom).
'following' means one lot of letters go next to another.
'trip' indicates an anagram.
'papal' is an anagram of 'appla'.
'use' after 'appla' is 'APPLAUSE'.
(Other definitions for applause that I've seen before include "Burst of clapping" , "Appreciative round?" , "Clapping of hands" , "1a [BACALL] was in this musical" , "Appreciative claps" .)