The most common and most likely answer to this crossword clue is the 14 letter word WHIPPERSNAPPER
I've seen this crossword clue in The Guardian
W
H
I
P
P
E
R
S
N
A
P
P
E
R
More clues leading to the result WHIPPERSNAPPER
- Cheeky youngster? The person administering corporal punishment's the head
- Fish given to one with cat, perhaps an impish young one?
- Rascal one stealing fish
- Pipsqueak, one sleeping alongside thieves?
- Little lad, one flogging camera?
- Wife in a photograph with a young rascal
- Young rascal, one stealing fish
- Upstart kinky sex type who takes pictures
- Kid with trendier photographer
- Cheeky kid who’s taken a shot of a shoplifter?
Buddy explains!

The straight part
We know that "Little lad" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case little lad = whippersnapper.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 WHIPPERSNAPPER mean?
WHIPPERSNAPPER noun- A young and cheeky or presumptuous person.