Injury allowed to cut short career (6)
I believe the answer is:
hurtle
'career' is the definition.
(I've seen this before)
'injury allowed to cut short' is the wordplay.
'injury' becomes 'hurt' ('hurt' can be a synonym of 'injury').
'allowed' becomes 'let' (I've seen this before).
'to cut short' means to remove the last letter.
'let' with its final letter taken away is 'le'.
'hurt'+'le'='HURTLE'
(Other definitions for hurtle that I've seen before include "Rush headlong" , "Dash, move at high speed" , "Proceed quickly and noisily" , "Move fast; rhymes with marine reptile" , "Lacking speed" .)