One dropping off fish? (6)
I believe the answer is:
kipper
'fish?' is the definition.
(type of fish)
I don't 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 "(Fishy) type of tie" , "Cured or smoked herring" , "Preserved herring" , "Cured fish (one having forty winks?)" , "being in bed?" .)