Clergyman accepting a power plant (7)
I believe the answer is:
reactor
'power plant' is the definition.
(I've seen this in another clue)
'clergyman accepting a' is the wordplay.
'clergyman' becomes 'rector' (rector is a kind of clergyman).
'accepting' is an insertion indicator (inserted letters are accepted).
'rector' placed around 'a' is 'REACTOR'.
(Other definitions for reactor that I've seen before include "Nuclear energy source" , "Provider of nuclear power" , "Device to produce energy by nuclear fission" , "device that's energy-producing" , "Heart of a nuclear power station" .)