The one running round is creating a disturbance (5)
I believe the answer is:
noise
'a disturbance' is the definition.
('noise' can be a synonym of 'disturbance')
'the one running round is' is the wordplay.
'running' indicates an anagram.
'round' means one lot of letters goes inside another.
'one' with letters rearranged gives 'noe'.
'noe' placed around 'is' is 'NOISE'.
'creating' is the link.
(Other definitions for noise that I've seen before include "Racket, din" , "Sound of any kind" , "Row" , "explosive report, for example" , "Unwanted sound" .)