Did smoking make it sleepy? (6)
I believe the answer is:
kipper
'it sleepy?' is the definition.
The definition suggests a singular noun which matches the answer.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for kipper that I've seen before include "has been caught napping" , "Cured or smoked herring" , "(Fishy) type of tie" , "part of breakfast?" , "One drops off" .)