The most common and most likely answer to this crossword clue is the 4 plus 4 plus 7 letter word FLEX ONES MUSCLES
F
L
E
X
O
N
E
S
M
U
S
C
L
E
S
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.