In the tournament level four I can’t score very high... what’s the trick?

Wait to use the power ups until after you’ve cleared that trio of white things that hold things up in the middle. Then use both Power ups and aim for the center. You want to hit that cluster of two trapped mice at the top.

In the meantime, keep the multipliers going as best you can. This will ensure a big payout when you finally got those two trapped mice. It’s easier if you use boosters but I just scored 53,000 without using them.