The most common and most likely answer to this crossword clue is the 10 letter word IDEALISTIC
I've seen this crossword clue in The Guardian
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More clues leading to the result IDEALISTIC
- Utopian novel italicised
- Romantic rendering italicised
- One is securing trade with credit, mostly? That’s impractical
- I get bogged down endlessly after I do business, and it’s impractical
- Starry-eyed setter visiting shop stocking article getting endless criticism
- One of French, most celebrated in Cannes, primarily as visionary
- Fish of the most important kind I start to collect – in aspiration
- Utopian cities laid waste
- Italicised “twirls” not practical
- Cities laid out in a way that’s impractical
Buddy explains!

The straight part
We know that "not practical" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not practical = idealistic.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 IDEALISTIC mean?
IDEALISTIC adjective- Of or pertaining to an idealist or to idealism.