Tostada alternative (4)
I believe the answer is:
taco
'tostada alternative' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for taco that I've seen before include "Tortilla rolled round a filling" , "Mexican snack" , "Set of three" , "quick dish" , "Mexican rolled pancake with a filling" .)