tighten up vs trammel

tighten up is not a noun while trammel is a noun.

Word	Noun	Adjective	Verb	Adverb
tighten up	No	No	Yes	No
trammel	Yes	No	Yes	No

As verbs, trammel is a hypernym of tighten up; that is, trammel is a word with a broader meaning than tighten up:

Other hypernyms of tighten up include bound, confine, limit, restrict, throttle.

tighten up (noun)	trammel (noun)
	a restraint that confines or restricts freedom (especially something used to tie down or restrain a prisoner)
	a restraint that is used to teach a horse to amble
	an adjustable pothook set in a fireplace
	a fishing net with three layers; the outer two are coarse mesh and the loose inner layer is fine mesh

tighten up (verb)	trammel (verb)
severely restrict in scope or extent	place limits on (extent or amount or access)
	catch in or as if in a trap