The most common and most likely answer to this crossword clue is the 5 plus 2 plus 8 letter word STAND UP PADDLING
I've seen this crossword clue in Independent
S
T
A
N
D
U
P
P
A
D
D
L
I
N
G
Buddy explains!
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.