Footballers' exchange covered by radio network (3-3)
I believe the answer is:
Here is my best explanation:
'footballers' exchange' is the definition.
(type of pass in football)
'covered by radio network' is the subsidiary indication.
'covered by' indicates a hidden word.
'onetwo' is hidden within 'radio network'.
(Other definitions for one-two that I've seen before include "Blow using fists' digits", "Swift couple of blows at boxing", "Boxing or soccer manoeuvre", "Pair of blows in boxing", "Interpassing at football - left-right at boxing" and "Pair of punches with both hands in quick succession".)