Banshee disturbed insignificant individual (3-4)
I believe the answer is:
has-been
'insignificant individual' is the definition.
'has-been' can be an answer for 'individual' (has-been is a kind of individual). I'm not certain of the 'insignificant' bit.
'banshee disturbed' is the wordplay.
'disturbed' is an anagram indicator.
'banshee' is an anagram of 'HAS-BEEN'.
Can you help me to learn more?
(Other definitions for has-been that I've seen before include "Person no longer famous, like banshee" , "Banshee (anag.)" , "Person no longer of consequence" , "One-time leading light who's faded" , "Person no longer famous or successful" .)