Deal with English missile going west (5)
I believe the answer is:
trade
'deal with' is the definition.
(thesaurus)
'english missile going west' is the wordplay.
'english' becomes 'e' (abbreviation).
'missile' becomes 'dart' (dart is a kind of missile).
'going west' is a reversal indicator (letters heading to the west or left).
'e'+'dart'='edart'
'edart' in reverse letter order is 'TRADE'.
(Other definitions for trade that I've seen before include "Commerce - traffic" , "Commercial exchange of goods and services" , "Buy and sell in business" , "Give and receive (blows)" , "Buying/selling of goods" .)