Account in connection with amount of land (4)
I believe the answer is:
acre
'amount of land' is the definition.
(I've seen this before)
'account in connection with' is the wordplay.
'account' becomes 'ac'.
'in connection with' becomes 're' (regarding).
'ac'+'re'='ACRE'
(Other definitions for acre that I've seen before include "Ancient city in Israel" , "Imperial unit of area" , "once occupied by Crusaders" , "marine location in Israel" , "Unit of land area" .)