Fencing position needs a brief moment — and energy (7)

I believe the answer is:

seconde

'fencing position' is the definition.
(I've seen this in another clue)

'a brief moment and energy' is the wordplay.
'a brief moment' becomes 'second' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'energy' becomes 'e' (physics symbol as in E=mc2).
'second'+'e'='SECONDE'

'needs' is the link.

I've seen this clue in The Guardian.

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