Mounting appeal to Anglicans to reflect (4)
I believe the answer is:
echo
'reflect' is the definition.
(thesaurus)
'mounting appeal to anglicans' is the wordplay.
'mounting' says the letters should be written in reverse (going up in a down clue).
'appeal' becomes 'oh'.
'to anglicans' becomes 'ce' (Church of England).
'oh'+'ce'='ohce'
'ohce' written backwards gives 'ECHO'.
'to' is the link.
(Other definitions for echo that I've seen before include "repercussion" , "A natural sound reflection" , "Repetition of sound" , "One who slavishly copies" , "next to delta" .)