Initially a canteen or shop providing services (5)

I believe the answer is:

naafi

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

'services' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for naafi that I've seen before include "WW2 canteen" , "Military facility" , "Caterers" , "Forces' canteen or shop" , "Forces 17" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app