Weighs on (6)
I believe the answer is:
haunts
'weighs on' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for haunts that I've seen before include "Places frequented" , "Frequently visited places, hangouts" , "Frequents or visits as a ghost" , "Places where ghosts hang out?" , "Frequently visits" .)