Have a go at judge? (3)
I believe the answer is:
try
I believe this clue is a double definition.
'have a go at' is the first definition.
(to have a go at something is to try it)
'judge?' is the second definition.
(as in trialling a defendant)
(Other definitions for try that I've seen before include "irritate" , "Aim" , "A rugby score crossing the line" , "Make an attempt" , "crack" .)