Best six won fighting for this in court (7,3)

I believe the answer is:

witness box

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

'in court' is the definition.
(I know that witness box is part of court)

'best six won fighting' is the wordplay.
'fighting' indicates an anagram (I've seen this in other clues).
'best'+'six'+'won'='bestsixwon'
'bestsixwon' is an anagram of 'WITNESS-BOX'.

'for this' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for witness box that I've seen before include "Courtroom enclosure" , "From where one testifies" , "Place for giving evidence" .)

I've seen this clue in The Telegraph.

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