Strength needed for finishing the race? (5)

I believe the answer is:

force

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'strength' is the definition.
(I know that strength can be written as force)

'for finishing the race?' is the wordplay.
'finishing the race?' becomes 'ce' (I can't explain this - if you can you should give a lot more credence to this answer).
'for'+'ce'='FORCE'

'needed' is the link.

Can you help me to learn more?

(Other definitions for force that I've seen before include "Physical coercion" , "Powerful effect or influence" , "Compulsion - police" , "Physical strength" , "Vehemence" .)

I've seen this clue in the Evening Standard.

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