The most common and most likely answer to this crossword clue is the 3 letter word DNA
I've seen this crossword clue in The Guardian
D
N
A
More clues leading to the result DNA
Buddy explains!
The straight part
We know that "It makes us" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it makes us = dna.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 DNA mean?
DNA noun- The part of a living being that carries genetic information.
- A biopolymer of deoxyribonucleic acid (a type of nucleic acid) that has four different chemical groups, called bases: adenine, guanine, cytosine, and thymine.
- The fundamental values or vision of an organization.