The most common and most likely answer to this crossword clue is the 8 letter word CASTRATO
I've seen this crossword clue in Independent
C
A
S
T
R
A
T
O
More clues leading to the result CASTRATO
- Old-time singer and performers meeting retired sailor at end of oratorio
- A guitar in care of a singer, formerly
- Old singer and players, one singing before 24 across
- He won’t reproduce form at start of Royal Ascot
- A guitar in care of male singer
- No balls help him to achieve high score
- Star act involved nothing this singer couldn’t reproduce!
- Find someone to play the scoundrel, old singer
- Co-star at bad singer
- Singer in company, soprano ultimately?
Buddy explains!

The straight part
We know that "he won’t reproduce (biologically)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case he won’t reproduce (biologically) = castrato.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 CASTRATO mean?
CASTRATO noun- A male who has been castrated, especially a male whose testicles have been removed before puberty in order to retain his boyish voice.
- A male soprano or alto voice produced by castration of the treble singer before puberty, intended to conserve his voice; the singer.
- Castrated; especially castrated prepubescently.
- Having, using or containing the voice of a castrato (noun).
- Originally composed for a castrato.