The most common and most likely answer to this crossword clue is the 5 letter word TACKY
I've seen this crossword clue in The Guardian
T
A
C
K
Y
More clues leading to the result TACKY
- Like a nail, perhaps, not quite dried?
- Food by end of day almost dry, perhaps, and tasteless
- Sticky and coarse
- Vulgar eccentric having head in textbook for week
- Naff, like a nail?
- Thanks to Calvin Klein, young are tasteless
- Tasteless adhesive
- Shabby, like equestrian gear?
- Lacking in taste, like gum
- Yacht’s beginning to change direction before getting slightly sticky
Buddy explains!

The straight part
We know that "Naff" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case naff = tacky.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 TACKY mean?
TACKY adjective- Of a substance, slightly sticky.
- A scrubby, neglected horse.
- A person in a similar condition.
- Of low quality.
- In poor taste.
- Gaudy or flashy.
- Shabby, dowdy in one's appearance or dress.