Element of legalese perhaps avoided by judge (5)
I believe the answer is:
argon
'element' is the definition.
(argon is a chemical element)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for argon that I've seen before include "17 [GAS]" , "Noble gas, Ar" , "Gas, 1% of atmosphere" , "An insert gas to groan about" , "Inert gas, present in small amounts in the air" .)