Care to relax, after putting energy into a comic song (7,5)
I believe the answer is:
amazing grace
'song' is the definition.
(I've seen this before)
'care to relax after putting energy into a comic' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'care' is 'race' which is within the answer.
'energy' could be 'zing' (I've seen this before) and 'zing' is found within the answer.
'a' is present in the answer.
The remaining letters 'mag' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for amazing grace that I've seen before include "Hymn written by John Newton, 1779" , "Hymn that "sav'd a wretch like me"?" , "song" , "Noted words of praise" , "religious air" .)