The most common and most likely answer to this crossword clue is the 7 plus 6 plus 6 letter word PLAYING SECOND FIDDLE
I've seen this crossword clue in Financial Times
P
L
A
Y
I
N
G
S
E
C
O
N
D
F
I
D
D
L
E
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.