Shake bronco, perhaps riding it? (2,9)
I believe the answer is:
on horseback
'riding it?' is the definition.
I know nothing about this answer so I can't judge whether this works.
'shake bronco perhaps' is the wordplay.
'perhaps' indicates an anagram.
'shake'+'bronco'='shakebronco'
'shakebronco' is an anagram of 'ON HORSEBACK'.
Can you help me to learn more?
(Other definitions for on horseback that I've seen before include "for such devils?" , "In the saddle" .)