The most common and most likely answer to this crossword clue is the 11 letter word PERMUTATION
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Buddy explains!

The straight part
We know that "change in condition" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case change in condition = permutation.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 PERMUTATION mean?
PERMUTATION noun- One of the ways something exists, or the ways a set of objects can be ordered.
- A one-to-one mapping from a finite set to itself.
- An ordering of a finite set of distinct elements.
- A transformation of a set's prime form, by applying one or more of certain operations, specifically, transposition, inversion, and retrograde.