The most common and most likely answer to this crossword clue is the 7 letter word PLUMPER
I've seen this crossword clue in The Sunday Telegraph
P
L
U
M
P
E
R
More clues leading to the result PLUMPER
Buddy explains!
The straight part
We know that "One making definite choice/less slim" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one making definite choice/less slim = plumper.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 PLUMPER mean?
PLUMPER adjective- Having a full and rounded shape; chubby, somewhat overweight.
- Fat.
- Sudden and without reservation; blunt; direct; downright.
- One who plumps or swells out something else.
- That which plumps or swells out something else.
- Hence, something carried in the mouth to distend the cheeks.
- In elections, a vote given to one candidate only, when two or more are to be elected, thus giving him or her the advantage over the others; a person who gives his or her vote thus is said to plump, or to plump his or her vote.
- A voter who plumps his or her vote.
- A downright, unqualified lie.
- An obese woman, especially in pornography.