Sweet song from a couple, including large contralto (6)
I believe the answer is:
dulcet
'sweet' is the definition.
(I know that sweet can be written as dulcet)
'couple including large contralto' is the wordplay.
'couple' becomes 'duet' (synonyms).
'including' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'contralto' becomes 'c' (musical abbreviation).
'l'+'c'='lc'
'duet' going around 'lc' is 'DULCET'.
'song from a' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for dulcet that I've seen before include "Harmonious, melodious" , "(Of sound) melodious" , "DT clue (anag.)" , "Mellifluous, pleasant to the ear" , "Agreeable and soothing to the ear" .)