Kidnapped a British editor on Tube (8)
I believe the answer is:
abducted
'kidnapped' is the definition.
('abduct' can be a synonym of 'kidnap')
'a british editor on tube' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'editor' becomes 'ed'.
'on' is a charade indicator (letters next to each other).
'tube' becomes 'duct' (I've seen this before**).
'ed' after 'duct' is 'ducted'.
'a'+'b'+'ducted'='ABDUCTED'
(Other definitions for abducted that I've seen before include "carried off" , "Kidnapped, snatched" .)