All Saints' day: miserable Serbian city (4,3)

I believe the answer is:

novi sad

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

'serbian city' is the definition.
(I've seen this before)

'all saints' day miserable' is the wordplay.
'all saints' day' becomes 'novi' (I can't explain this - if you can you should believe this answer much more).
'miserable' becomes 'sad' (similar in meaning).
'novi'+'sad'='NOVI SAD'

Can you help me to learn more?

(Other definitions for novi sad that I've seen before include "Serbian city" , "European port" , "Serbian town" .)

I've seen this clue in The Independent.

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