My French bird, it has four legs! (8)
I believe the answer is:
mongoose
'it has four legs' is the definition.
The definition suggests a singular noun which matches the answer.
'my french bird' is the wordplay.
'my french' becomes 'mon' ('my' in French).
'bird' becomes 'goose' (goose is a kind of bird).
'mon'+'goose'='MONGOOSE'
Can you help me to learn more?
(Other definitions for mongoose that I've seen before include "Cat-like creature with long body and bushy tail" , "Slayer of snakes" , "Animal that kills snakes" , "Agile cat-like creature with long body and tail" , "Small mammal that preys on snakes" .)