The most common and most likely answer to this crossword clue is the 6 letter word CLINGY
I've seen this crossword clue in Financial Times
C
L
I
N
G
Y
More clues leading to the result CLINGY
Buddy explains!

The straight part
We know that "Tending to stick" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tending to stick = clingy.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 CLINGY mean?
CLINGY adjective- Having a tendency to cling.
- (usually derogatory) Pathetically attached to, or possessive of someone, usually a significant other.