Rules game depended on team leader's score (6)
I believe the answer is:
result
'score' is the definition.
(I've seen this before)
'rules game depended on team leader's' is the wordplay.
I cannot quite see how this works, but
an anagram of 'rules' is 'resul' which is present in the answer.
A single letter 't' 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?
(Other definitions for result that I've seen before include "Consequence or effect" , "'Outcome, upshot (6)'" , "Verdict" , "Final outcome" , "Final score" .)