Crossword Genius

Where to shop for everything at Maidenhead (4)

Ross

I believe the answer is:

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

'where to shop' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

'everything at maidenhead' is the wordplay.
'everything' becomes 'all' (I've seen this before).
'at' says to put letters next to each other (I've seen this in other clues).
'maidenhead' becomes 'm' (head letter of 'maiden').
'all' put after 'm' is 'MALL'.

'for' is the link.

Can you help me to learn more?

(Other definitions for mall that I've seen before include "Public walk", "Shopping precinct", "Shopping area closed to vehicles", "Covered shopping centre", "Pedestrian shopping area".)

I've seen this clue in Evening Standard.