Code word for S (6)
I believe the answer is:
sierra
'code word for s' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sierra that I've seen before include "Mountain range -- code word for S" , "A Spanish mountain chain (6)" , "Vehicle" , "Mountain range in Spanish-speaking countries" , "Spanish range of mountains" .)