The most common and most likely answer to this crossword clue is the 4 letter word DIET
I've seen this crossword clue in The Times
D
I
E
T
More clues leading to the result DIET
- Pass on first of tips in attempt to lose weight
- Eat less — stop before end of dessert!
- Buy it, trying at first to control weight
- Conference stamp on source of taxes
- Attempt perhaps to streamline assembly
- What one is allowed to eat in foreign parliament?
- Special catering arrangement for assembly
- Regime followed by slimmer assembly
- The German model for an assembly in 17A
- Regime in parliament, say
Buddy explains!

The straight part
We know that "attempt to lose weight" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case attempt to lose weight = diet.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 DIET mean?
DIET noun- The food and beverage a person or animal consumes.
- A controlled regimen of food and drink, as to gain or lose weight or otherwise influence health.
- (by extension) Any habitual intake or consumption.
- (of a food or beverage) Containing less fat, salt, sugar, or calories than normal, or claimed to have such.
- Having certain traits subtracted.
- To regulate the food of (someone); to put on a diet.
- To modify one's food and beverage intake so as to decrease or increase body weight or influence health.
- To eat; to take one's meals.
- To cause to take food; to feed.
- (usually capitalized as a proper noun) A council or assembly of leaders; a formal deliberative assembly.
- A session of exams
- The proceedings under a criminal libel.
- A clerical or ecclesiastical function in Scotland.