Mountains showing some displacement to the west (4)
I believe the answer is:
alps
'mountains' is the definition.
(alp is a kind of mountain)
'some displacement to the west' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'to the west' shows that the letters should be reversed in order.
'spla' is hidden within 'displacement'.
'spla' reversed gives 'ALPS'.
'showing' acts as a link.
(Other definitions for alps that I've seen before include "Mont Blanc is therein" , "Laps around mountains" , "Mountain system, highest peak Mont Blanc" , "Slap (anag.)" , "European mountain range" .)