The most common and most likely answer to this crossword clue is the 7 letter word OLESTRA
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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 OLESTRA mean?
OLESTRA noun- A fat substitute (a glyceride of sucrose) that cannot be easily digested and therefore adds no fat, calories, or cholesterol to food products; also used as an industrial lubricant.