The most common and most likely answer to this crossword clue is the 10 plus 5 letter word FOUNDATION STONE
I've seen this crossword clue in The Daily Telegraph
F
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More clues leading to the result FOUNDATION STONE
- Located article, one among many with sound structural basis
- Discovered on site — not a terribly good basis for building
- Aunt fed onions to gathering as basic necessity
- Start building station — one will commemorate the event
- Basically it's laid to start building up
- Supporter of building establishment having a certain weight
Buddy explains!
The straight part
We know that "good basis for building" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case good basis for building = foundation stone.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.