The most common and most likely answer to this crossword clue is the 8 letter word CULTURED
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "learned" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case learned = cultured.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 CULTURED mean?
CULTURED verb- To maintain in an environment suitable for growth (especially of bacteria) (compare cultivate)
- To increase the artistic or scientific interest (in something) (compare cultivate)
- Learned in the ways of civilized society; civilized; refined.
- Artificially developed.