Special vehicle race in this country grass (6,4)
I believe the answer is:
flying boat
'special vehicle' is the definition.
'flying boat' can be an answer for 'vehicle' (flying boat is a kind of vehicle). I am not certain of the 'special' bit.
'race in this country grass' is the wordplay.
'race' becomes 'fly' (fly can mean to race around).
'this country' becomes 'GB' (Great Britain).
'grass' becomes 'oat' (oat is a type of grass).
'fly'+'in'+'gb'+'oat'='FLYING-BOAT'
Can you help me to learn more?
(Other definitions for flying boat that I've seen before include "Specialised craft" , "Seaplane" , "Plane landing on water" .)