Half of standard radio confirmation (5)
I believe the answer is:
roger
'radio confirmation' is the definition.
(I've seen this before)
'half of standard' is the wordplay.
'half of' means to take half the letters.
'standard' becomes 'jolly roger' (I've seen this before).
'jollyroger' halved is 'ROGER'.
(Other definitions for roger that I've seen before include "- - Moore (007)" , "I've got the message" , "Have sex" , "man, > I understand" , "Man's name" .)