It's for fencing sheep enclosure, a little to the north (4)
I believe the answer is:
epee
'it's for fencing' is the definition.
(type of sword used in fencing)
'sheep enclosure a little to the north' is the wordplay.
'a little' indicates the answer is hidden within the clue.
'to the north' says the letters should be written in reverse (in a down clue, letters go up or 'northward').
'eepe' is hidden within 'sheep enclosure'.
'eepe' in reverse letter order is 'EPEE'.
(Other definitions for epee that I've seen before include "Fencing sword, heavier than a foil" , "Sharp-pointed duelling sword" , "Fencing weapon" , "Narrow fencing sword" , "Fencing blade" .)