How do I delete the content after the specified character in the clipboard?

[guxianbang]

I want to delete the content behind "aaa" and become like this:

j1aaaFish

After processing：

j1aaa

More examples:

gf2aaaFood
om2aaaBanana

[gglick]

Use this regex:

(?<=aaa).*

in a Search and Replace action with the clipboard (make sure it searches for a regular expression, not a string):

[guxianbang]

Thank you very much for your help！