make a clean breast of vs fess up

make a clean breast of and fess up both are verbs.

Word	Noun	Adjective	Verb	Adverb
make a clean breast of	No	No	Yes	No
fess up	No	No	Yes	No

As verbs, make a clean breast of and fess up are synonyms defined as:

make a clean breast of and fess up: admit or acknowledge a wrongdoing or error

Other synonyms of make a clean breast of include own up.

make a clean breast of (verb)	fess up (verb)
admit or acknowledge a wrongdoing or error	admit or acknowledge a wrongdoing or error