Split tender includes religious group with energy (8)
I believe the answer is:
bisected
'split' is the definition.
(I've seen this before)
'tender includes religious group with energy' is the wordplay.
'tender' becomes 'bid' ('bid' can be a synonym of 'tender').
'includes' means one lot of letters goes inside another.
'religious group' becomes 'sect' (I've seen this before).
'with' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mc2).
'sect'+'e'='secte'
'bid' placed around 'secte' is 'BISECTED'.
(Other definitions for bisected that I've seen before include "Cut in half" , "Cut into two, halved" , "Cut into two equal parts" , "split" , "Divided into two equal parts" .)