shit vs take a shit

shit is a noun but take a shit is not a noun.

Word	Noun	Adjective	Verb	Adverb
shit	Yes	No	Yes	No
take a shit	No	No	Yes	No

As verbs, shit and take a shit are synonyms defined as:

Other synonyms of shit include ca-ca, crap, defecate, make, stool, take a crap.

shit (noun)	take a shit (noun)
something of little value
Obscene word for unacceptable behavior
insulting terms of address for people who are stupid or irritating or ridiculous
a coarse term for defecation
a small worthless amount
obscene terms for feces

shit (verb)	take a shit (verb)
have a bowel movement	have a bowel movement
give away information about somebody