The most common and most likely answer to this crossword clue is the 12 letter word GREENSLEEVES
I've seen this crossword clue in Independent
G
R
E
E
N
S
L
E
E
V
E
S
More clues leading to the result GREENSLEEVES
- Healthy food reportedly goes for a song
- Air essentially unchanged for centuries!? Environmental group reportedly splits
- Cabbages and bits of lettuce perhaps voiced in song
- My delight no longer conveyed in song
- Traditional number of vegetables nearly always consumed by the French
- Playing seven reels; e.g., Yuletide song
Buddy explains!
The straight part
We know that "song" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case song = greensleeves.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.