Consent from top admitting Church doctrine's first (6)
I believe the answer is:
accede
'consent' is the definition.
(thesaurus)
'top admitting church doctrine's first' is the wordplay.
'top' becomes 'ace' (**).
'admitting' means one lot of letters goes inside another.
'church' becomes 'ce' (abbreviation for Church of England).
'first' says to take the initial letters.
The first letter of 'doctrines' is 'd'.
'ce'+'d'='ced'
'ace' enclosing 'ced' is 'ACCEDE'.
'from' acts as a link.
(Other definitions for accede that I've seen before include "'Acquiesce, defer (6)'" , "Comply" , "Grant, agree to proposal" , "Agree to what is proposed" , "Assume" .)