Pontifical comrade coming round every year (5)
I believe the answer is:
Here is my best explanation:
'pontifical' is the definition.
'comrade coming round every year' is the subsidiary indication.
'comrade' becomes 'pal' (I've seen this in other clues).
'coming round' means one lot of letters goes inside another.
'every year' becomes 'pa' (per annum).
'pal' enclosing 'pa' is 'papal'.
(Other definitions for papal that I've seen before include "of Catholic high-up", "Of the RC leader", "Relating to the Pope", "Like some bulls", "Of the highest Vatican authority", "Of the pope" and "Relating to the Pontiff".)