Catch sight of peaks to the west (4)
I believe the answer is:
spot
'catch sight of' is the definition.
(to spot is to notice or catch sight of)
'peaks to the west' is the wordplay.
'peaks' becomes 'tops' ('top' can be a synonym of 'peak').
'to the west' says the letters should be written in reverse (letters written right to left or 'east to west').
'tops' written backwards gives 'SPOT'.
(Other definitions for spot that I've seen before include "Catch sight of - pimple" , "awkward situation" , "point on snooker table" , "See; round mark" , "Drop of rain" .)