When the best return after taking half of Europe, they get a landmass (7)
I believe the answer is:
eurasia
'a landmass' is the definition.
(Eurasia is an example)
'when the best return after taking half of' is the wordplay.
'when' becomes 'as'.
'the best' becomes 'ai' (resembles 'Ae', old-fashioned term for excellent).
'return' shows that the letters should be reversed in order.
'after' is a charade indicator (letters next to each other).
'taking half of' becomes 'eur' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ai' written backwards gives 'ia'.
'as'+'ia'='asia'
'asia' after 'eur' is 'EURASIA'.
'europe they get' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for eurasia that I've seen before include "Huge area" , "Large landmass combining two continents" , "Unbroken landmass bearing two continents" , "Turkey, and so on" , "Two continents considered as one" .)