Beat in some small disturbance (3)
I believe the answer is:
lam
'beat' is the definition.
(I've seen this before)
'some small disturbance' is the wordplay.
'some' says to take the centre.
'disturbance' indicates anagramming the letters.
The middle letters of 'small' are 'mal'.
'mal' with letters rearranged gives 'LAM'.
'in' is the link.
(Other definitions for lam that I've seen before include "pelt" , "hurried flight" , "US criminals commonly escape?" , "Flee hastily" , "Thrash; (US) escape" .)