Upcoming street art's no medium to hold show (11)
I believe the answer is:
demonstrate
'show' is the definition.
('demonstrate' can be a synonym of 'show')
'upcoming street art's no medium to hold' is the wordplay.
'upcoming' is a reversal indicator.
'to hold' indicates a hidden word (I've seen 'held' mean this).
'etartsnomed' can be found hidden inside 'street arts no medium'.
'etartsnomed' backwards is 'DEMONSTRATE'.
(Other definitions for demonstrate that I've seen before include "Review" , "Prove, show" , "Make a public protest" , "English floozies returning, led by villainous character" , "Show or display" .)