1. Conducted with or marked by hidden aims or methods
   "clandestine intelligence operations"
   - cloak-and-dagger, hole-and-corner, hugger-mugger, hush-hush, secret, surreptitious, undercover, underground

See also: covert

Encyclopedia: Clandestine

• at an equal rate
• at any cost
• at any expense
• at any rate
• at arm's length
• at bay
• at best
• at bottom
• at close range
• at fault
• at first
• at first blush
• at first glance
• at first hand
• at first sight
• at hand
• at heart
• at home
• at issue
• at large
• at last
• at least
• at leisure
• at length
• at loggerheads