Apply oneself in fierce contest (3,2)
I believe the answer is:
set to
'apply oneself' is the definition.
(as in setting oneself to a task)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for set to that I've seen before include "closed" , "Start - fight (3,2,3-2)" , "Ding-dong" , "Altercation" , "Row" .)