Hard to get Mark to join Anglicans (6)
I believe the answer is:
scarce
'hard to get' is the definition.
(I've seen this in another clue)
'mark to join anglicans' is the wordplay.
'mark' becomes 'scar' (mark left by an injury).
'to join' is a charade indicator (letters next to each other).
'anglicans' becomes 'ce' (Church of England).
'scar'+'ce'='SCARCE'
(Other definitions for scarce that I've seen before include "Hard to get" , "Not enough to satisfy demand" , "Deficient in quantity" , "Common? Definitely not" , "Not often come across" .)