The most common and most likely answer to this crossword clue is the 10 letter word DISTRACTED
I've seen this crossword clue in The Sunday Telegraph
D
I
S
T
R
A
C
T
E
D
More clues leading to the result DISTRACTED
Buddy explains!

The straight part
We know that "not paying attention" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not paying attention = distracted.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 DISTRACTED mean?
DISTRACTED verb- To divert the attention of.
- To make crazy or insane; to drive to distraction.
- Having one's attention diverted; preoccupied
- Distraught