Bone lad broke near the knuckle (6)
I believe the answer is:
ribald
'near the knuckle' is the definition.
(I've seen this before)
'bone lad broke' is the wordplay.
'bone' becomes 'rib' (rib is a kind of bone).
'broke' is an anagram indicator.
'lad' is an anagram of 'ald'.
'rib'+'ald'='RIBALD'
(Other definitions for ribald that I've seen before include "Bawdy and vulgar" , "Indecent" , "Humorous in vulgar or disrespectful way" , "Humorously vulgar" , "Coarse" .)