Those voting in the lector at evensong? (10)
I believe the answer is:
electorate
'those voting' is the definition.
(voters in an election)
'in the lector at evensong?' is the wordplay.
'in' indicates a hidden word.
'ELECTORATE' is hidden within 'the lector at evensong'.
(Other definitions for electorate that I've seen before include "Voters collectively" , "Constituency" , "choosing body" , "Those entitled to vote" , "Voters as a whole" .)