The most common and most likely answer to this crossword clue is the 11 letter word SUBSTANTIAL
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More clues leading to the result SUBSTANTIAL
Buddy explains!

The straight part
We know that "considerable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case considerable = substantial.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 SUBSTANTIAL mean?
SUBSTANTIAL noun- Anything having substance; an essential part.
- Having a substance; actually existing.
- Not imaginary; real; actual; true; veritable.
- Corporeal; material; firm.
- Having good substance; strong; stout; solid; firm.
- Possessed of goods or an estate; moderately wealthy.
- Large in size, quantity, or value; ample; significant.
- Most important; essential.
- Satisfying; having sufficient substance to be nourishing or filling.