Just find underground in Paris is speedier at heart (13)

I believe the answer is:

disinterested

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

'just' is the definition.
(thesaurus)

'underground in paris is speedier at heart' is the wordplay.
'underground' becomes 'disinter' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in paris is' becomes 'est' ('is' in French).
'at heart' means to look at the middle letters.
The middle of 'speedier' is 'ed'.
'disinter'+'est'+'ed'='DISINTERESTED'

'find' is the link.

Can you help me to learn more?

(Other definitions for disinterested that I've seen before include "Not expecting any profit" , "With no axe to grind" , "Feeling no concern" , "Impartial" , "Unbiased" .)

I've seen this clue in The Telegraph.

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.