Find doing something they shouldn't and dismiss (5)
I believe the answer is:
catch
'dismiss' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for catch that I've seen before include "Snag - trap" , "Dismiss (batsman); break (in voice)" , "Fly in the ointment" , "Apprehend - funny song" , "Capture; hidden problem" .)