Places crossed by Agricola coming west (4)
I believe the answer is:
loci
'places' is the definition.
(I've seen this before)
'crossed by agricola coming west' is the wordplay.
'crossed by' indicates a hidden word.
'coming west' says the letters should be written in reverse (letters go right to left or 'east to west').
'icol' is hidden within 'agricola'.
'icol' backwards is 'LOCI'.
(Other definitions for loci that I've seen before include "locations" , "Points where something occurs; coil (anag.)" , "Particular positions" , "sites" , "Particular places" .)