It's a loner disturbing members of the family (9)
I believe the answer is:
relations
'members of the family' is the definition.
(I've seen this before)
'it's a loner disturbing' is the wordplay.
'disturbing' is an anagram indicator.
'its'+'a'+'loner'='itsaloner'
'itsaloner' is an anagram of 'RELATIONS'.
(Other definitions for relations that I've seen before include "kindred?" , "Kinsfolk's" , "liaison" , "Sex" , "They're connected by blood or marriage" .)