One must do so or die in the attempt! (3)
I believe the answer is:
eat
'one must do so or die' is the definition.
I can't judge whether this defines the answer.
'in the attempt' is the wordplay.
'in' says the answer is hidden in the clue.
'EAT' can be found hidden inside 'the attempt'.
Can you help me to learn more?
(Other definitions for eat that I've seen before include "Have 23d [MEAL]" , "Take food" , "Do cats - bats? Do bats - cats? (Alice in Wonderland)" , "Devour" , "to do etching?" .)