Telegraph covering working street artist (9)
I believe the answer is:
constable
'artist' is the definition.
(painter John Constable)
'telegraph covering working street' is the wordplay.
'telegraph' becomes 'cable' (synonyms).
'covering' indicates putting letters inside.
'working' becomes 'on' (e.g. a machine is working or on).
'street' becomes 'st' (abbreviation).
'on'+'st'='onst'
'cable' enclosing 'onst' is 'CONSTABLE'.
(Other definitions for constable that I've seen before include "Copper - artist" , "Flatford Mill painter" , "Bobby" , "CARRY ON FILM" , "Did he have a brush" .)