Alarming vehicle in outer Surrey (5)
I believe the answer is:
scary
'alarming' is the definition.
('scary' can be similar in meaning to 'alarming')
'vehicle in outer surrey' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle**).
'in' is an insertion indicator.
'outer' means to remove the middle letters.
'surrey' with its middle removed is 'sy'.
'car' inserted inside 'sy' is 'SCARY'.
(Other definitions for scary that I've seen before include "Fearsome" , "[SPICE]" , "spook" , "Frightening or spooky" , "Hair-raising" .)