Make anxious (7)
(Other definitions for disturb that I've seen before include "Interrupt (sleep)" , "Interrupt, annoy" , "Interrupt; upset" , "Interfere with" , "Break" .)
'make anxious' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for perturb that I've seen before include "Disturb the composure of" , "Disconcert" , "Opera star" , "Unsettle, make anxious" , "Make unsettled" .)