At snooker, it means a rest for one's opponent (5)
I believe the answer is:
break
This could be a double definition.
'at snooker' is the first definition.
The definition and answer can be both acts as well as being singular nouns.
I also know that 'snooker' relates to this answer.
'it means a rest for one's opponent' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for break that I've seen before include "that a billiards player wants as high as possible?" , "accumulation of points" , "Holiday; decipher (code)" , "Vacation; snap" , "Shatter; respite" .)