strike up

strike up  {v.}

1a. To start to sing or play.

We were sitting around the camp fire. Someone struck up a song, and we all joined in.

The President took his place on the platform, and the band struck up the national anthem.

1b. To give a signal to start (a band) playing.

When the team ran on the field, the band director struck up the band.

2. To bring about; begin; start.

The policeman struck up a conversation with John while they were waiting for the bus.