The most common and most likely answer to this crossword clue is the 5 plus 2 letter word CLEAN UP
I've seen this crossword clue in The Sunday Telegraph
C
L
E
A
N
U
P
More clues leading to the result CLEAN UP
- Profit greatly in contest, keeping in shape?
- Remove dirt and make a fortune?
- Played fairly, winning - make a great profit?
- Be inclined to enter contest free from corruption
- Make a killing, then remove all evidence of it?
- Rest to enter competition to make big bucks
- Incline to get aboard vessel free of filth
- Bank stopping competition to make big profits
- Inclination to enter competition to make a great profit
- Make a bundle tilt inside container
Buddy explains!

The straight part
We know that "Make a bundle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case make a bundle = clean up.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.
What does CLEAN UP mean?
CLEAN UP noun- The act of cleaning or tidying something.
- Fourth in the batting order; a cleanup hitter.