The most common and most likely answer to this crossword clue is the 4 letter word ELLA
I've seen this crossword clue in The Guardian
E
L
L
A
More clues leading to the result ELLA
- Had lilies regularly dropped round for girl
- Dad abandons Spanish dish for this woman
- A couple of lines penned by each girl
- Austen novel's central characters take a step back for another woman
- Spanish translations of ‘the girl‘
- Woman from Spain that’s upset everyone
- Other versions of the jazz singer
- She turns up in several legends
- Great interpreter of 8 21 25
- Liberal, fifty, being hugged by each woman
Buddy explains!

The straight part
We know that "jazz singer /jazz singer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jazz singer /jazz singer = ella.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.