A trick that can get a man dismissed (5)
I believe the answer is:
catch
'a trick' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for catch that I've seen before include "Grasp - overtake - overhear - surprise" , "Disadvantage that's hidden" , "Stop the motion, of a ball say" , "Intercept and hold" , "fellow hooked for matrimony?" .)