Backer, sound, icy and heavenly (7)

I believe the answer is:

angelic

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'heavenly' is the definition.
(relating to angels or heaven)

'backer sound icy' is the wordplay.
'backer' becomes 'angel' (an angel is a financial backer).
'sound icy' becomes 'ic' (I can't justify this - if you can you should believe this answer much more).
'angel'+'ic'='ANGELIC'

'and' acts as a link.

Can you help me to learn more?

(Other definitions for angelic that I've seen before include "Extremely well-behaved" , "Sweet and well-behaved" , "Like heavenly beings" , "Nice gal (anag.)" , "Very well behaved" .)

I've seen this clue in the Sydney Morning Herald.

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