Cry when husband leaves for a fly-by-night? (3)
I believe the answer is:
owl
'a fly-by-night?' is the definition.
(creature which flies at night)
I don't understand how the remainder of the clue works.
(Other definitions for owl that I've seen before include "eg Snowy, Tawny" , "One flying" , "Nightbird" , "Member of Parliament" , "Winged hooter" .)