Left Edna to show strategic advantage (8)
I believe the answer is:
leverage
'strategic advantage' is the definition.
(I've seen this before)
'left edna' is the wordplay.
I cannot quite see how this works, but
'left' could be 'l' (common abbreviation) and 'l' is present in the answer.
The remaining letters 'everage' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'to show' acts as a link.
Can you help me to learn more?
(Other definitions for leverage that I've seen before include "Capacity to exert pressure" , "financial advantage" , "Economic clout" , "Purchase" , "Power of achievement; (US) gearing" .)