The most common and most likely answer to this crossword clue is the 2 plus 2 plus 3 plus 7 letter word GO TO ANY LENGTHS
I've seen this crossword clue in Independent
G
O
T
O
A
N
Y
L
E
N
G
T
H
S
Buddy explains!
The straight part
We know that "Do whatever it takes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case do whatever it takes = go to any lengths.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.