Take care of a rook left injured (4,5)
I believe the answer is:
look after
'take care of' is the definition.
('look after' can be a synonym of 'take care of')
'a rook left injured' is the wordplay.
'injured' indicates anagramming the letters.
'a'+'rook'+'left'='arookleft'
'arookleft' with letters rearranged gives 'LOOK AFTER'.
(Other definitions for look after that I've seen before include "Tend" , "Supervise" , "Watch over" , "Take care of" , "mind" .)