The most common and most likely answer to this crossword clue is the 4 letter word PLUM
P
L
U
M
More clues leading to the result PLUM
Buddy explains!

The straight part
We know that "purple" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case purple = plum.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 PLUM mean?
PLUM noun- The fruit and its tree.
- Extended senses.
- Of a dark bluish-red colour.
- Choice; especially lavish or preferred.
- To plumb.
- Plumb
- Completely; utterly.