nail down

(verb) succeed in obtaining a position. Synonyms: nail down, nail, peg. Example: "He nailed down a spot at harvard."

(verb) define clearly. Synonyms: pin down, peg down, nail down, narrow down, narrow, specify. Example: "I cannot narrow down the rules for this game."

(verb) make final; put the last touches on; put into final form. Synonyms: finalize, finalise, settle, nail down. Example: "Let's finalize the proposal."