From Spain to Siberia (7)
I believe the answer is:
eurasia
'from spain to siberia' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eurasia that I've seen before include "Combined continent" , "Landmass extending from Cape Roca in the west to Cape Dezhnev in the east" , "World's largest land mass" , "large part of world" , "Largest landmass" .)