He tries to do his job (5)
I believe the answer is:
judge
'he tries' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for judge that I've seen before include "rule" , "Decide a legal case" , "Magistrate" , "Adjudicator" , "Form an opinion of" .)