Baseless bit of satire is to go downhill (3)
I believe the answer is:
ski
This clue might be a double definition.
'baseless bit of satire' is the first definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'go downhill' is the second definition.
(go down a hill on skis)
'is to' is the link.
Can you help me to learn more?
(Other definitions for ski that I've seen before include "Aid to movement on snow" , "Piece of sports equipment" , "Slide downhill, sportingly" , "Mountain runner" , "Journey" .)