Recognise character on the radio? (3)
I believe the answer is:
see
'recognise' is the definition.
(both can mean to notice)
'character on the radio?' is the wordplay.
'character' becomes 'c'.
'on the radio?' indicates a 'sounds like' (homophone) clue (I've seen 'on the radio' mean this).
'c' sounds like 'SEE'.
(Other definitions for see that I've seen before include "Observe the bishop's domain" , "Rome, notably" , "Perceive with eyes or mind" , "Visualise" , "District of a bishop - or Pope" .)