Game Boy not opening for Oliver Stone (4)
I believe the answer is:
ruby
'stone' is the definition.
(I've seen this in other clues)
'game boy not opening for oliver' is the wordplay.
I cannot really see how this works, but
'game' could be 'ru' (rugby union) and 'ru' is found within the answer.
'boy' could be 'b' (abbreviation used in schools) and 'b' is found in the answer.
A single letter 'y' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ruby that I've seen before include "Deep 6 across" , "Deep red variety of corundum" , "Gemstone - shade of red" , "Completely" , "Vivid red" .)