make it one's business
Undertake a self-appointed task, as in I'll make it my business to find out their plans. This phrase was first recorded in 1642.
Words nearby make it one's business
make heavy weather,
make history,
make inroads into,
make it,
make it hot for,
make it one's business,
make it snappy,
make it up,
make it with,
make light of,
make like