The most common and most likely answer to this crossword clue is the 7 letter word BEQUEST
I've seen this crossword clue in The Guardian
B
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More clues leading to the result BEQUEST
Buddy explains!

The straight part
We know that "Legacy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case legacy = bequest.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 BEQUEST mean?
BEQUEST noun- The act of bequeathing or leaving by will.
- The transfer of property upon the owner's death according to the will of the deceased.
- That which is left by will; a legacy.
- That which has been handed down or transmitted.
- A person's inheritance; an amount of property given by will.
- To give as a bequest; bequeath.