nail down vs succeed

nail down and succeed both are verbs.

Word	Noun	Adjective	Verb	Adverb
nail down	No	No	Yes	No
succeed	No	No	Yes	No

As verbs, succeed is a hypernym of nail down; that is, succeed is a word with a broader meaning than nail down:

Other hypernyms of nail down include bring home the bacon, come through, deliver the goods, win.

nail down (verb)	succeed (verb)
make final; put the last touches on; put into final form	attain success or reach a desired goal
define clearly	be the successor (of)
succeed in obtaining a position