digital clock vs clock

digital clock and clock both are nouns.

Word	Noun	Adjective	Verb	Adverb
digital clock	Yes	No	No	No
clock	Yes	No	Yes	No

As nouns, clock is a hypernym of digital clock; that is, clock is a word with a broader meaning than digital clock:

digital clock (noun)	clock (noun)
a clock that displays the time of day digitally	a timepiece that shows the time of day

digital clock (verb)	clock (verb)
	measure the time or duration of an event or action or the person who performs an action in a certain period of time