Scheme requiring energy instead of quiet style (4)
I believe the answer is:
elan
'style' is the definition.
(synonyms)
'scheme requiring energy instead of quiet' is the wordplay.
I cannot really understand how this works, but
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is present in the answer.
The remaining letters 'lan' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for elan that I've seen before include "Impetuosity - style" , "Vigour, panache" , "Vivacity, dash" , "Energy, style and enthusiasm" , "Combination of style and vigour" .)