Staff adopting American way (4)
I believe the answer is:
road
'way' is the definition.
(road is a kind of way)
'staff adopting american' is the wordplay.
'staff' becomes 'rod' (I've seen this before).
'adopting' means one lot of letters goes inside another.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'rod' going around 'a' is 'ROAD'.
(Other definitions for road that I've seen before include "Way from A to B" , "Way travelled by boat" , "For place to anchor" , "mine gallery" , "Route travelled by sea" .)