The most common and most likely answer to this crossword clue is the 8 letter word BEEBREAD
I've seen this crossword clue in The Guardian
B
E
E
B
R
E
A
D
Buddy explains!
The straight part
We know that "what workers feed their youngsters" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what workers feed their youngsters = beebread.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 BEEBREAD mean?
BEEBREAD noun- Bee pollen with added honey and bee secretions, made and stored in brood cells by forager bees, and used as food for worker bees and larvae.