Constantly worry about something (6)
I believe the answer is:
obsess
(Other definitions for obsess that I've seen before include "Prey on" , "Think only" , "brood" , "Be constantly talking about" , "Be constantly preoccupied" .)
I believe the answer is:
obsess
(Other definitions for obsess that I've seen before include "Prey on" , "Think only" , "brood" , "Be constantly talking about" , "Be constantly preoccupied" .)