The most common and most likely answer to this crossword clue is the 6 letter word KLUDGE
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Buddy explains!

The straight part
We know that "Makeshift device" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case makeshift device = kludge.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 KLUDGE mean?
KLUDGE noun- (electronics engineering) An improvised device, typically crudely constructed to test the validity of a principle before doing a finished design.
- Any construction or practice, typically crude yet effective, designed to solve a problem temporarily or expediently.
- An amalgamated mass of unrelated parts.
- A badly written or makeshift piece of software; a hack.
- To build or use a kludge.