Suffer injury despite message of good luck (5,1,3)
I believe the answer is:
break a leg
'suffer injury despite message of good luck' is the definition.
I can't tell whether this definition defines the answer.
'injury despite message of good luck' is the wordplay.
I cannot really understand how this works, but
'injury' could be 'break' (break is a kind of injury) and 'break' is found within the answer.
'good' could be 'g' (abbreviation) and 'g' is located in the answer.
The remaining letters 'ale' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for break a leg that I've seen before include "Good luck in the theatre!" , "Thespian's good luck! (slang)" , "Actors' good luck" , "but not on the piste" , "Do something that requires surgery" .)