Game over, then toss second over (7)
I believe the answer is:
diabolo
'second over' is the definition.
The definition suggests a singular noun which matches the answer.
'game over then toss' is the wordplay.
'game' becomes 'diablo' (traditional toy).
'over' is an insertion indicator.
'then toss' becomes 'o' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'diablo' going around 'o' is 'DIABOLO'.
Can you help me to learn more?
(Other definitions for diabolo that I've seen before include "Game involving two sticks joined by a string and a spool-shaped object" , "Top-on-a-string game" , "Devilish" , "Game of catching spinning-top" , "Game involving sticks and spinning top" .)