The most common and most likely answer to this crossword clue is the 11 letter word CEMENTATION
I've seen this crossword clue in The Times
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Buddy explains!
The straight part
We know that "sticking together" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sticking together = cementation.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 CEMENTATION mean?
CEMENTATION noun- The act of cementing
- The impregnation of the surface of a metal with another material; the manufacture of steel by carburizing iron
- The precipitation of mineral matter in the pores of a sediment
- The use of a cement join the parts of a broken bone to aid in the healing process
- The use of a cement or adhesive to fasten orthodontics or to restore chipped or broken teeth