One arranged with regard for a music producer (4,5)
I believe the answer is:
reed organ
'a music producer' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'one arranged with regard' is the wordplay.
'arranged with' indicates anagramming the letters.
'one' with its letters mixed up with 'regard' makes 'REED-ORGAN'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for reed organ that I've seen before include "supports traditional services" , "small instrument" , "Melody Maker?" , "Keyboard instrument, harmonium" , "musical instrument" .)