The most common and most likely answer to this crossword clue is the 10 letter word INTEGRATES
I've seen this crossword clue in The Guardian
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Buddy explains!

The straight part
We know that "Makes whole" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case makes whole = integrates.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 INTEGRATES mean?
INTEGRATES verb- To form into one whole; to make entire; to complete; to renew; to restore; to perfect.
- To include as a constituent part or functionality.
- To indicate the whole of; to give the sum or total of; as, an integrating anemometer, one that indicates or registers the entire action of the wind in a given time.
- To subject to the operation of integration; to find the integral of.
- To desegregate, as a school or neighborhood.
- To combine compatible elements in order to incorporate them.