Partly missing urban term for joking (6)
I believe the answer is:
banter
'joking' is the definition.
(thesaurus)
'partly missing urban term' is the wordplay.
'partly' indicates the answer is hidden within the clue.
'BANTER' can be found hidden inside 'missing urban term'.
'for' acts as a link.
(Other definitions for banter that I've seen before include "Rail" , "Good-natured repartee" , "Light-hearted raillery" , "Humorous ridicule" , "Good-natured teasing" .)