The most common and most likely answer to this crossword clue is the 13 letter word NUTRITIONISTS
I've seen this crossword clue in The Daily Telegraph
N
U
T
R
I
T
I
O
N
I
S
T
S
Buddy explains!
The straight part
We know that "They want us to take things in properly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they want us to take things in properly = nutritionists.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 NUTRITIONISTS mean?
NUTRITIONISTS noun- An expert or specialist in nutrition or nutritionistics