Declared in France: 'Friend means warmth' (10)

I believe the answer is:

amiability

I'm a little stuck... Click here to teach me more about this clue!

'declared in france' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'friend means warmth' is the wordplay.
'friend' becomes 'ami' (I've seen this before).
'means warmth' becomes 'ability' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ami'+'ability'='AMIABILITY'

Can you help me to learn more?

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.