Farm unit (4)
'farm unit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for acre that I've seen before include "holy city" , "Imperial unit of area" , "Care about the piece of land" , "Care about this bit of land" , "4840 sq yds" .)
(Other definitions for bale that I've seen before include "Group" , "Bundle of hay or cotton" , "(Make into a) bundle of hay" , "Evil - bundle" , "Unit of hay" .)