Challenge Tory over care (7)
I believe the answer is:
contend
'challenge' is the definition.
'tory over care' is the wordplay.
'tory' becomes 'con' (I've seen this before).
'over' means one lot of letters go next to another.
'care' becomes 'tend' (I've seen this before).
'con'+'tend'='CONTEND'
(Other definitions for contend that I've seen before include "Debate - contest - claim" , "Compete; deal (with)" , "Compete, vie" , "Struggle (with someone)" , "Maintain" .)