Crossword Genius

Spill lime and soda over men returning to supply toilets (6,4)

Ross

I believe the answer is:

ladies room

'spill' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

I've seen this clue in The Guardian.
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