“I’m making a cuppa”? Bringing in drop of ristretto would be a subversive act (7)
I believe the answer is:
treason
'act' is the definition.
(treason is a kind of act)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for treason that I've seen before include "One rats (anag)" , "Act of betrayal of a government" , "One's art? (anag)" , "Stare on (anag.)" , "Criminal attempt to overthrow a government" .)