The most common and most likely answer to this crossword clue is the 5 letter word BINDI
I've seen this crossword clue in Independent
B
I
N
D
I
Buddy explains!

The straight part
We know that "facial decoration" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case facial decoration = bindi.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 BINDI mean?
BINDI noun- The “holy dot” traditionally worn on the forehead of married Hindu women.
- Makeup or jewellery worn in imitation of such a dot.
- The common lawn weed, Soliva sessilis, introduced to Australia from South America.
- A seed of this plant, having small sharp spines which stick painfully into bare feet.
- Any of a number of plants of the genus Calotis which have small burrs with fine barbed awns.
- Any of a various plants of the genus Sclerolaena.