Deer sprint round back of broken barrier (9)
I believe the answer is:
hindrance
'barrier' is the definition.
(thesaurus)
'deer sprint round back of broken' is the wordplay.
'deer' becomes 'hind' (hind is a kind of deer**).
'sprint' becomes 'race' (I've seen this before).
'round' is an insertion indicator.
'back of' indicates one should take the final letters.
The last letter of 'broken' is 'n'.
'race' placed around 'n' is 'rance'.
'hind'+'rance'='HINDRANCE'
(Other definitions for hindrance that I've seen before include "Obstacle" , "Something that holds back" , "Nicer hand (anag.)" , "Delay to overcome" , "Block to progress" .)