single-reed instrument vs reed

single-reed instrument and reed both are nouns.

Word	Noun	Adjective	Verb	Adverb
single-reed instrument	Yes	No	No	No
reed	Yes	No	No	No

As nouns, reed is a hypernym of single-reed instrument; that is, reed is a word with a broader meaning than single-reed instrument:

single-reed instrument: a beating-reed instrument with a single reed (as a clarinet or saxophone)
reed: a musical instrument that sounds by means of a vibrating reed

Other hypernyms of single-reed instrument include beating-reed instrument, reed instrument.

single-reed instrument (noun)	reed (noun)
a beating-reed instrument with a single reed (as a clarinet or saxophone)	a musical instrument that sounds by means of a vibrating reed
	a vibrator consisting of a thin strip of stiff material that vibrates to produce a tone when air streams over it
	tall woody perennial grasses with hollow slender stems especially of the genera Arundo and Phragmites