Farewell heard when mother leaves for Indian city (6)
I believe the answer is:
mumbai
'for indian city' is the definition.
(I've seen this before)
'farewell heard when mother' is the wordplay.
I cannot quite see how this works, but
'mother' could be 'mum' (informal term for mother) and 'mum' is located in the answer.
The remaining letters 'bai' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'leaves' acts as a link.
Can you help me to learn more?
(Other definitions for mumbai that I've seen before include "City once called Bombay" , "state capital" , "Bombay since 1995" , "place in India" , "Formerly Bombay" .)