Find eastern wagon heading west (5)
I believe the answer is:
trace
'find' is the definition.
(thesaurus)
'eastern wagon heading west' is the wordplay.
'eastern' becomes 'e'.
'wagon' becomes 'cart' (cart is a kind of wagon).
'heading west' shows that the letters should be reversed in order.
'e'+'cart'='ecart'
'ecart' written backwards gives 'TRACE'.
(Other definitions for trace that I've seen before include "Follow and find" , "Very small amount that can only just be detected" , "Discover whereabouts" , "Find; copy; small amount" , "Track down or make copy" .)