Crime close to cricket ground (7)
I believe the answer is:
Here is my best explanation:
'crime' is the definition.
(treason is a kind of crime)
'to cricket ground' is the subsidiary indication.
'to cricket' becomes 't' (I am not sure about this - if you are sure you should believe this answer much more).
'ground' becomes 'reason' ('reason' can be a synonym of 'ground').
'close' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
(Other definitions for treason that I've seen before include "A crime", "Disloyalty (to one's country)", "Gunpowder Plot, say", "Senator? (Anag)", "serious crime", "Perfidy", "Crime of national betrayal", "LEse-majestE", "Senator (anag)" and "Betrayal (of one's country)".)