Sea creature found in motor car (4)
I believe the answer is:
orca
'sea creature' is the definition.
(term for a killer whale)
'in motor car' is the wordplay.
'in' says the answer is hidden in the clue.
'ORCA' can be found hidden inside 'motor car'.
'found' acts as a link.
(Other definitions for orca that I've seen before include "Marine creature" , "Cor! a killer whale" , "Large predator" , "Massive killer" , "Large mammal" .)