Mexican snack filled with beans occasionally and this sauce? (7)
I believe the answer is:
tabasco
'this sauce?' is the definition.
(Tabasco sauce is an example)
'mexican snack filled with beans occasionally' is the wordplay.
'mexican snack' becomes 'taco' (I've seen this in another clue).
'filled with' means one lot of letters goes inside another.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
The alternate letters of 'beans' are 'bas'.
'taco' enclosing 'bas' is 'TABASCO'.
'and' is the link.
(Other definitions for tabasco that I've seen before include "Mexican state; pungent sauce" , "ASBO Act (anag) - hot stuff!" , "Red pepper sauce" , "Hot peppery sauce" , "Mexico state" .)