Hard-working, when our team falls kind of flat (6)

I believe the answer is:

studio

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

'kind of flat' is the definition.
(I know that studio is a type of apartment)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for studio that I've seen before include "Artist's workroom - film company" , "Elstree area" , "Workroom for 27 down" , "Centre for movie-making" , "Unpleasant vapour" .)

I've seen this clue in The Independent.

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