clandestine vs hole-and-corner

clandestine and hole-and-corner both are adjectives.

Word	Noun	Adjective	Verb	Adverb
clandestine	No	Yes	No	No
hole-and-corner	No	Yes	No	No

As adjectives, clandestine and hole-and-corner are synonyms defined as:

clandestine and hole-and-corner: conducted with or marked by hidden aims or methods

Other synonyms of clandestine include cloak-and-dagger, hugger-mugger, hush-hush, secret, surreptitious, undercover, underground.

clandestine (adjective)	hole-and-corner (adjective)
conducted with or marked by hidden aims or methods	conducted with or marked by hidden aims or methods
	relating to the peripheral and unimportant aspects of life