The most common and most likely answer to this crossword clue is the 10 letter word FLAUNCHING
I've seen this crossword clue in The Guardian
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Buddy explains!

The straight part
We know that "concrete structure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case concrete structure = flaunching.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 FLAUNCHING mean?
FLAUNCHING verb- To provide with flaunching.
- The sloped mortar fillet around the base of a chimney pot, which serves to hold the pot in position and allow rainwater to run off.
- A mortar fillet at the junction of the chimney stack and the roof; superseded in modern times by lead flashing.