Huge land mass, like one close to Africa (4)
I believe the answer is:
asia
'huge land mass' is the definition.
(I've seen this in another clue)
'like one close to africa' is the wordplay.
'like' becomes 'as'.
'one' becomes 'i' (Roman numeral).
'close to' suggests the final letters (the close/ending of).
The final letter of 'africa' is 'a'.
'as'+'i'+'a'='ASIA'
(Other definitions for asia that I've seen before include "Stretch of land" , "Populous area" , "group of countries" , "Continent in which India is situated" , "Part of the world" .)