Drive into Split, fencing off some land (4-3)
I believe the answer is:
rear-end
'drive into' is the definition.
'split fencing off some land' is the wordplay.
'split' becomes 'rend' (I've seen this before).
'fencing off' means one lot of letters goes inside another.
'some land' becomes 'are' (historical unit of measurement - 100 square metres).
'rend' placed around 'are' is 'REAR-END'.
(Other definitions for rear-end that I've seen before include "Crash into another vehicle from behind (US)" , "hit a vehicle" , "Crash into back of another vehicle" .)