Might one crow, when dog gets empty eggshell? (8)
I believe the answer is:
cockerel
'might one crow' is the definition.
(cockerels crow in the morning)
'dog gets empty eggshell?' is the wordplay.
'dog' becomes 'cocker' (cocker is a kind of dog).
'gets empty' means to remove the middle letters (I've seen 'getting emptied' mean this (the inside letters are emptied out)).
'eggshell' with its middle removed is 'el'.
'cocker'+'el'='COCKEREL'
'when' acts as a link.
(Other definitions for cockerel that I've seen before include "Young domestic cock" , "Young domestic male fowl" , "He's liable to crow" , "Farmyard bird" , "Young male bird" .)