Understood by a select few (8)
I believe the answer is:
esoteric
'understood by a select few' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for esoteric that I've seen before include "needing privy" , "Tie score (anagram)" , "Understandable by only an enlightened inner circle" , "Privileged or confidential among coteries" , "not generally understood" .)