The most common and most likely answer to this crossword clue is the 4 plus 3 plus 7 letter word RING THE CHANGES
I've seen this crossword clue in Financial Times
R
I
N
G
T
H
E
C
H
A
N
G
E
S
More clues leading to the result RING THE CHANGES
Buddy explains!
The straight part
We know that "Use a variety of approaches" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case use a variety of approaches = ring the changes.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.