Reveal song by Rod first to exec (3,4)
I believe the answer is:
lay bare
'reveal' is the definition.
(I've seen this in another clue)
'song by rod first to exec' is the wordplay.
'song' becomes 'lay' (poetic term for a song).
'by' is a charade indicator (letters next to each other).
'rod' becomes 'bar' (I've seen this before).
'first to' suggests taking the first letters.
The first letter of 'exec' is 'e'.
'lay'+'bar'+'e'='LAY BARE'
(Other definitions for lay bare that I've seen before include "Expose" , "Show clearly, disclose" .)