It's hard to find the right amount of land (4)
I believe the answer is:
rare
'it's hard to find' is the definition.
(I've seen this in another clue)
'right amount of land' is the wordplay.
'right' becomes 'r' (common abbreviation).
'amount of land' becomes 'are' (I can't justify this - if you can you should believe this answer much more).
'r'+'are'='RARE'
'the' acts as a link.
Can you help me to learn more?
(Other definitions for rare that I've seen before include "Seldom - unusual" , "Unusual(ly fine)" , "Not found often" , "Choice - lightly cooked - thin" , "Infrequent; remarkable" .)