Collocations for instrumental - adj.

be, prove
become

highly, very
essentially, largely
merely
purely

in
They were highly instrumental in bringing the business to Newtown.

be

largely, mostly
The songs are largely instrumental.

entirely, purely
The album was entirely instrumental.
He's created a purely instrumental score.

Instrumental is used with these nouns:
accompaniment, composition, interlude, music, passage, prelude, role, texture, track