Masterful play on Radio Three to start with (6)
I believe the answer is:
adroit
'masterful' is the definition.
(I've seen this in another clue)
'play on radio three to start with' is the wordplay.
'play' is an anagram indicator.
'on' is a charade indicator (letters next to each other).
'to start with' indicates taking the first letters.
The first letter of 'three' is 't'.
'radio' next to 't' is 'radiot'.
'radiot' is an anagram of 'ADROIT'.
(Other definitions for adroit that I've seen before include "Skilled" , "resourceful" , "Deft and skilful" , "Skilful, dexterous" , "Clever - crafty" .)