The most common and most likely answer to this crossword clue is the 12 letter word RATIONALISES
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result RATIONALISES
Buddy explains!

The straight part
We know that "Makes sense" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case makes sense = rationalises.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 RATIONALISES mean?
RATIONALISES verb- To make something rational or more rational.
- To justify an immoral act, or illogical behaviour. “The process of thought by which one justifies a discreditable act, and by which one offers to oneself and the world a better motive for one's action than the true motive”
- To remove radicals, without changing the value of an expression or the roots of an equation.
- To structure something along modern, efficient and systematic lines, or according to scientific principles. This often includes eliminating duplication and grouping like or similar items.