Underground vehicle taken back with awful Yank initially (6)
I believe the answer is:
subway
'underground' is the definition.
('subway' can be a synonym of 'underground')
'vehicle taken back with awful yank initially' is the wordplay.
'vehicle' becomes 'bus' (I've seen this before).
'taken back' shows that the letters should be reversed in order.
'initially' indicates taking the first letters.
The first letters of 'with awful yank' is 'way'.
'bus' backwards is 'sub'.
'sub'+'way'='SUBWAY'
(Other definitions for subway that I've seen before include "US underground railway" , "American tube" , "Pedestrian underpass" , "New York's "tube"" , "New York city trains" .)