The most common and most likely answer to this crossword clue is the 4 plus 3 plus 3 letter word JUST THE JOB
I've seen this crossword clue in The Daily Telegraph
J
U
S
T
T
H
E
J
O
B
Buddy explains!
The straight part
We know that "Exactly what’s needed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case exactly what’s needed = just the job.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.