Singer Jones carries on, not yet proven (7)
I believe the answer is:
alleged
'not yet proven' is the definition.
(an allegation must be proved)
'singer jones carries on' is the wordplay.
'singer jones' becomes 'Aled' (Aled Jones is a Welsh singer).
'carries' means one lot of letters goes inside another (inserted letters carried inside).
'on' becomes 'leg' (cricket term, fielding positions).
'aled' going around 'leg' is 'ALLEGED'.
(Other definitions for alleged that I've seen before include "Claimed (without proof)" , "Asserted in court" , "Declared without being able to prove" , "So-called" , "Declared without proof" .)