Scoundrels begin calling after disturbance starts (4)
I believe the answer is:
cads
'scoundrels' is the definition.
(a cad is a dishonourable person)
'begin calling after disturbance starts' is the wordplay.
'begin' says to take the initial letters.
The initial letters of 'calling after disturbance starts' is 'CADS'.
(Other definitions for cads that I've seen before include "'Blackguards, bounders (4)'" , "Rotters" , "Knaves" .)