The most common and most likely answer to this crossword clue is the 5 plus 2 plus 4 letter word BRING TO BEAR
B
R
I
N
G
T
O
B
E
A
R
Buddy explains!
The straight part
We know that "exercise" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case exercise = bring to bear.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.