Single out third of the elders in church (6)
I believe the answer is:
select
'single out' is the definition.
(I've seen this before)
'third of the elders in church' is the wordplay.
'third of the elders' becomes 'le' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'church' becomes 'sect' (sect is a kind of church).
'le' put within 'sect' is 'SELECT'.
Can you help me to learn more?
(Other definitions for select that I've seen before include "best" , "Single out" , "Choice, picked out" , "Choose from a number of alternatives" , "Of superior quality" .)