Clear and decisive poll on religious education (10)
I believe the answer is:
resounding
'clear and decisive' is the definition.
(resounding means clear or unambiguous)
'poll on religious education' is the wordplay.
'poll' becomes 'sounding' (a poll sounds people's views out).
'on' says to put letters next to each other.
'religious education' becomes 'RE' (abbreviation).
'sounding' after 're' is 'RESOUNDING'.
(Other definitions for resounding that I've seen before include "Booming" , "Decisive" .)