Something frowned on in court that whoppers and howlers have in common? (7,8)

I believe the answer is:
leading question
'common?' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'something frowned on in court that whoppers and howlers have' is the wordplay.
I cannot really understand how this works, but
'on' is within the answer.
'in' is found in the answer.
'have' could be 'lead' (leading is a kind of having) and 'lead' is found within the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for leading question that I've seen before include "Shouldn't someone recommended be concert-master" , "One may be asked by counsel" , "That which prompts the answer required" .)
