The most common and most likely answer to this crossword clue is the 12 letter word TEMPERATURES
I've seen this crossword clue in The Guardian
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More clues leading to the result TEMPERATURES
Buddy explains!
The straight part
We know that "Nurses take them" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nurses take them = temperatures.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.
Crossword Answer definitions
TEMPERATURES noun- A measure of cold or heat, often measurable with a thermometer.
- An elevated body temperature, as present in fever and many illnesses.
- A property of macroscopic amounts of matter that serves to gauge the average intensity of the random actual motions of the individually mobile particulate constituents. http//arxiv.org/pdf/physics/0004055
- The state or condition of being tempered or moderated.
- The balance of humours in the body, or one's character or outlook as considered determined from this; temperament.