The most common and most likely answer to this crossword clue is the 4 plus 5 letter word LIME GREEN
I've seen this crossword clue in The Times
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More clues leading to the result LIME GREEN
Buddy explains!

The straight part
We know that "shade" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shade = lime green.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 LIME GREEN mean?
LIME GREEN adjective- Having a bright, light-green colour, like that of a lime.