Obstacle course evacuated after deer bolted (9)
I believe the answer is:
hindrance
'obstacle' is the definition.
(a hindrance is an obstacle or barrier)
'course evacuated after deer bolted' is the wordplay.
'evacuated' says to hollow out the word (remove centre letters).
'after' says to put letters next to each other.
'deer' becomes 'hind' (hind is a kind of deer).
'bolted' becomes 'ran' (I've seen this in another clue).
'course' with its middle taken out is 'ce'.
'hind'+'ran'='hindran'
'ce' put after 'hindran' is 'HINDRANCE'.
(Other definitions for hindrance that I've seen before include "Chain nerd up - it delays progress" , "bar" , "Something inhibiting action" , "Delay to overcome" , "Nicer hand (anag.)" .)