Believe part of play about church power (6)
I believe the answer is:
accept
'believe' is the definition.
(I've seen this before)
'play about church power' is the wordplay.
'play' becomes 'act' (synonyms).
'about' indicates putting letters inside.
'church' becomes 'ce' (abbreviation for Church of England).
'power' becomes 'p' (symbol in physics).
'ce'+'p'='cep'
'act' going around 'cep' is 'ACCEPT'.
'part of' is the link.
(Other definitions for accept that I've seen before include "Take on; tolerate" , "Receive voluntarily" , "Believe to be correct; take on" , "agree to buy" , "Take as a gift" .)