Bit of backbone shown by green energy supporter (8)
I believe the answer is:
vertebra
'bit of backbone' is the definition.
('vertebra' is part of 'backbone')
'by green energy supporter' is the wordplay.
'by' is a charade indicator (letters next to each other).
'green' becomes 'vert' (I've seen this before).
'energy' becomes 'e' (physics symbol as in E=mce).
'supporter' becomes 'bra' (a bra gives support to breasts).
'vert'+'e' is 'verte'.
'verte'+'bra'='VERTEBRA'
'shown' acts as a link.
(Other definitions for vertebra that I've seen before include "Backbone segment" , "Segment of the spine" , "Spinal bone" , "Part of backbone" , "Part of the spine" .)