The most common and most likely answer to this crossword clue is the 11 letter word ADOLESCENCE
I've seen this crossword clue in The Daily Telegraph
A
D
O
L
E
S
C
E
N
C
E
More clues leading to the result ADOLESCENCE
- Youth taking beer outside party caught in commotion
- Youth in case once led astray
- Conservative featured in Panorama supporting a welfare payment for teens
- Youth has trouble with classes, I’d say
- Youth beginning to arrange deal caught in a meltdown
- Teens caught in a social security spot
- A party with 100 in the French place — part of growing up
- Youth caught in a benefit environment
- Youthful period sadly ceased once around 50
- Regular cadence interrupted by Leo's blundering in the teen years
Buddy explains!

The straight part
We know that "Teens" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case teens = adolescence.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 ADOLESCENCE mean?
ADOLESCENCE noun- The transitional period of physical and psychological development between childhood and maturity.