Street phone cord (6)
I believe the answer is:
string
'cord' is the definition.
(string is a kind of cord)
'street phone' is the wordplay.
'street' becomes 'st' (abbreviation).
'phone' becomes 'ring' (to ring on the phone).
'st'+'ring'='STRING'
(Other definitions for string that I've seen before include "Number of racehorses" , "Suspend" , "Thin piece of cord" , "yarn" , "Length of narrow cord" .)