have a go at it vs pair

have a go at it is not a noun while pair is a noun.

Word	Noun	Adjective	Verb	Adverb
have a go at it	No	No	Yes	No
pair	Yes	No	Yes	No

As verbs, pair is a hypernym of have a go at it; that is, pair is a word with a broader meaning than have a go at it:

Other hypernyms of have a go at it include copulate, couple, mate.

have a go at it (noun)	pair (noun)
	two people considered as a unit
	a set of two similar things considered as a unit
	a poker hand with 2 cards of the same value
	two items of the same kind

have a go at it (verb)	pair (verb)
have sexual intercourse with	engage in sexual intercourse
	bring two objects, ideas, or people together
	arrange in pairs
	occur in pairs
	form a pair or pairs