The most common and most likely answer to this crossword clue is the 9 letter word PRIMITIVE
I've seen this crossword clue in The Guardian
P
R
I
M
I
T
I
V
E
More clues leading to the result PRIMITIVE
- Proper computer lessons I have, simple
- Proper musical makes brief comeback after one that’s crude
- Ancient priest, following an example, volunteers to quit
- I merit VIP treatment! Simple!
- Like 19 and 23, eating it with 4 is uncivilised
- I have to go beneath edge into hole first
- Following prudish sex this compiler’s crude
- Ancient VIP I repeatedly term ‘doddery’
- Demure, needing to get with it, I have to be Methodist
- Simple one this, not even, 5's this kind of number, catching it!
Buddy explains!

The straight part
We know that "Simple" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case simple = primitive.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 PRIMITIVE mean?
PRIMITIVE noun- An original or primary word; a word not derived from another, as opposed to derivative.
- A member of a primitive society.
- A simple-minded person.
- A data type that is built into the programming language, as opposed to more complex structures.
- Any of the simplest elements (instructions, statements, etc.) available in a programming language.
- A basic geometric shape from which more complex shapes can be constructed.
- A function whose derivative is a given function; an antiderivative.
- Of or pertaining to the beginning or origin, or to early times; original; primordial; primeval; first.
- Of or pertaining to or harking back to a former time; old-fashioned; characterized by simplicity.
- Crude, obsolete.
- (grammar) Original; primary; radical; not derived.
- Occurring in or characteristic of an early stage of development or evolution.
- Not derived from another of the same type
- Most recent common ancestor (often hypothetical) of