Ghostly lookalike (12)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
doppelganger
(Other definitions for doppelganger that I've seen before include "A person's spitting image" , "Ghostly double of a living person - green Lapp god (anag)" , "Ghostly double that haunts its living counterpart" , "Living person's double" , "Spirit double" .)