It's played with variations on strings (4,6)
I believe the answer is:
cats cradle
'with variations on strings' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'it's played' is the wordplay.
I cannot really understand how this works, but
'it's' could be 'ts' (abbreviation. e.g. in 'tis) and 'ts' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cats cradle that I've seen before include "Fun for string-players" , "Child's game involving fingers and string" , "Child's game played with string looped over the fingers" , "versatile string band?" , "jazz-fan's mecca, perhaps?" .)