Large landmass (7)
I believe the answer is:
eurasia
'large landmass' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for eurasia that I've seen before include "Supercontinent" , "Large landmass combining two continents" , "Largest landmass" , "Continental land mass" , "Unbroken landmass bearing two continents" .)