Woman in vehicle round loch (5)
I believe the answer is:
carol
'woman' is the definition.
'vehicle round loch' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'round' becomes 'o' (round can mean a round object).
'loch' becomes 'l'.
'car'+'o'+'l'='CAROL'
'in' acts as a link.
(Other definitions for carol that I've seen before include "Song, especially at Christmas" , "Song celebrating the birth of Jesus" , "See 1" , "and 27: Waits" , "Joyful hymn" .)