Devour in single attempt (3)
I believe the answer is:
eat
'devour' is the definition.
(to eat is to devour or consume)
'in single attempt' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EAT' is hidden within 'single attempt'.
(Other definitions for eat that I've seen before include "Use a knife and fork" , "to do etching?" , "Take food" , "Have 23d [MEAL]" , "tolerate in diet" .)