The most common and most likely answer to this crossword clue is the 16 letter word STATE-OF-THE-ART
I've seen this crossword clue in The Times
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More clues leading to the result STATE-OF-THE-ART
Buddy explains!
The straight part
We know that "Modern" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case modern = state-of-the-art.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 STATE-OF-THE-ART mean?
STATE-OF-THE-ART noun- The condition of scientific or technical knowledge, particularly the peak or highest level thereof, at a particular time.
- At the highest level of development at a particular time; cutting-edge.