Abandoned monopoly perhaps and revealed its secrets (4,3,4,4)
I believe the answer is:
gave the game away
'revealed its secrets' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'abandoned monopoly perhaps' is the wordplay.
I cannot quite see how this works, but
'perhaps' could be 'eg' (for example) and 'eg' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for gave the game away that I've seen before include "spilled beans?" , "Offered venison free of charge" , "what poacher handing out freebies did" , "Let on" .)