hold on vs clasp

hold on is not a noun while clasp is a noun.

Word	Noun	Adjective	Verb	Adverb
hold on	No	No	Yes	No
clasp	Yes	No	Yes	No

As verbs, clasp is a hyponym of hold on; that is, clasp is a word with a more specific, narrower meaning than hold on:

Other hyponyms of hold on include latch on, cling, hang.

hold on (noun)	clasp (noun)
	the act of grasping
	a fastener (as a buckle or hook) that is used to hold two things together

hold on (verb)	clasp (verb)
be persistent, refuse to stop	hold firmly and tightly
stop and wait, as if awaiting further instructions or developments	grasp firmly
hold the phone line open	fasten with a buckle or buckles
hold firmly	fasten with or as if with a brooch
retain possession of