Score mark when difficult game turns, keeping one in match (4,9)
I believe the answer is:
time signature
'score mark' is the definition.
'time signature' can be an answer for 'mark' (thesaurus). I am unsure of the 'score' bit.
'difficult game turns keeping one in match' is the wordplay.
I cannot really see how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is located in the answer.
This explanation may well be incorrect...
'when' acts as a link.
Can you help me to learn more?
(Other definitions for time signature that I've seen before include "Musical notation - intimate urges (anag)" , "guide for players" , "Indication of musical rhythm" , "Mark before the first bar?" , "Indicator on score of musical rhythm" .)