The most common and most likely answer to this crossword clue is the 7 letter word BONFIRE
I've seen this crossword clue in Independent
B
O
N
F
I
R
E
More clues leading to the result BONFIRE
Buddy explains!
The straight part
We know that "It burns primarily alight" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it burns primarily alight = bonfire.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.
What does BONFIRE mean?
BONFIRE noun- A fire in which bones are burned.
- A fire to burn unwanted or disreputable items or people: proscribed books, heretics etc.
- A large, controlled outdoor fire, as a signal or to celebrate something.
- To fire (pottery) using a bonfire.
- To make, or celebrate around, a bonfire.