She believed that she was an 'instrument' of God. [=she believed that God was using her to do things; she believed that God was acting through her]
Part of her training as a pilot involved learning to fly by 'instruments'. [=learning to fly only by looking at the instruments in the airplane]
Movies can be useful 'instruments' of social change. [=movies can be used to cause social change]
(..) Inspector Clouseau. You have a license? Monsieur? City ordinance B prohibits the playing... of any musical instrument in a public place... for the purpose of commercial enterprise without a license. - I don't understand. - It is against the "leau"... - for you to play your musical instrument. - The "leau"? - What? - You say it's against the "leau"? - Yes, unless you have a proper license. - What kind of license? (..)1975 The Return of the Pink Panther