Husband opening food store in megacity (5)
I believe the answer is:
delhi
'megacity' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's an association between them I don't understand?
'husband opening food store in' is the wordplay.
'opening' says to take the initial letters.
'food store' becomes 'deli' (short for delicatessen).
'in' indicates putting letters inside.
The first letter of 'husband' is 'h'.
'h' put inside 'deli' is 'DELHI'.
Can you help me to learn more?
(Other definitions for delhi that I've seen before include "Asian city" , "Old city of north central India" , "Capital of India" , "Indian capital city" , "New -, Asian capital" .)