Mrs Simpson's spread (5)
I believe the answer is:
marge
This clue is a double definition.
'mrs simpson's' is the first definition.
(I've seen this in other clues)
'spread' is the second definition.
(marge is a kind of spread)
(Other definitions for marge that I've seen before include "Lover of Homer" , "limit" , "little girl?" , "Homer's wife" , "Homer Simpson's wife; a spread (abbr.)" .)