Tortilla stuffed with beans, regularly lacking sauce (7)
I believe the answer is:
tabasco
'sauce' is the definition.
(Tabasco is an example)
'tortilla stuffed with beans regularly lacking' is the wordplay.
'tortilla' becomes 'taco' (I've seen this in another clue).
'stuffed with' is an insertion indicator (some letters get stuffed inside).
'regularly lacking' means one should take alternating letters (letters removed at regular intervals).
The alternating letters of 'beans' are 'bas'.
'taco' enclosing 'bas' is 'TABASCO'.
(Other definitions for tabasco that I've seen before include "Mexican state; pungent sauce" , "Mexico state" , "Hot sauce made from capsicums" , "Hot pepper sauce" , "Spicy pepper sauce" .)