Clandestine (adj): Secret or hidden. (चोरी छिपे का , गुप्त)
Synonyms: Surreptitious, Stealthy, Covert, Undercover, Furtive
Antonyms: Visible, Exposed, Open, Overt, Public
Example: Mr Vyas undertook many clandestine operations against the enemy countries.
This sinister entity is the self-appointed “guardian” of the Islamic state, and has an existential stake in keeping Kashmir ablaze through the steady, clandestine and deniable infusion of violence and terrorism.