Decline energy drinks at the outset (5)
I believe the answer is:
lapse
'decline' is the definition.
(I know that lapse is a more specific form of the action drop away)
'energy drinks at the outset' is the wordplay.
I cannot really understand how this works, but
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is present in the answer.
'drinks' could be 'laps' (lapping is a kind of drinking) and 'laps' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for lapse that I've seen before include "Brief failure (of concentration)" , "Decline into an inferior state" , "Momentary mistake" , "Pleas (anag)" , "Cease to be valid" .)