Deny judge silent non-starter (6)
I believe the answer is:
refute
'deny' is the definition.
(I've seen this before)
'judge silent non-starter' is the wordplay.
'judge' becomes 'ref' (referee).
'silent non starter' becomes 'ute' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ref'+'ute'='REFUTE'
Can you help me to learn more?
(Other definitions for refute that I've seen before include "Rebut; deny" , "Prove something to be wrong" , "Prove to be incorrect" , "Prove wrong; deny" , "Prove that statement or accusation is wrong" .)