Sandwich spread (9)
(Another definition for nutbutter that I've seen is " spread".)
'sandwich spread' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mayo that I've seen before include "Cold, creamy sauce (abbr)" , "Eg, Braeburn or Cox" , "Irish county; dressing" , "radio presenter" , "Irish county - sauce (abbr)" .)