Well I never! Disheartened after wife leaves, returning to cause some kind of alarm (8)
I believe the answer is:
reveille
'some kind of alarm' is the definition.
(military wake-up signal)
'well i never disheartened after wife leaves returning to cause' is the wordplay.
I cannot really understand how this works, but
'i' is present in the answer.
'cause' could be 'eve' (Eve is an example) and 'eve' is located in the answer.
This explanation may well be incorrect...
(Other definitions for reveille that I've seen before include "Soldiers' wake-up call" , "Military signal to wake up" , "What soldiers get up to" , "The wake-up army bugle call" , "Morning call" .)