Carry on with exercise run that's excruciating (9)
I believe the answer is:
persevere
'carry on' is the definition.
(I know that carry on can be written as persevere)
'with exercise run that's excruciating' is the wordplay.
'with' means one lot of letters go next to another.
'exercise' becomes 'pe' (Physical Education).
'run' becomes 'r' (cricket abbreviation).
'that's excruciating' becomes 'severe' (I can't explain this - if you can you should believe this answer much more).
'pe' next to 'r' is 'per'.
'per'+'severe'='PERSEVERE'
Can you help me to learn more?
(Other definitions for persevere that I've seen before include "Carry on regardless" , "Fight on" , "give it another try" , "Be persistent, refuse to stop" , "Be unwilling to stop" .)