Perhaps double fault takes Djokovic finally ahead (5,2)

I believe the answer is:

could be

I'm a little stuck... Click here to teach me more about this clue!

'fault takes djokovic finally ahead' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'perhaps double' is the wordplay.
I cannot really understand how this works, but
an anagram of 'double' is 'ouldbe' which is within the answer.
A single letter 'c' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in The Guardian.

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