The most common and most likely answer to this crossword clue is the 7 letter word SUPPOSE
I've seen this crossword clue in The Daily Telegraph
S
U
P
P
O
S
E
More clues leading to the result SUPPOSE
- Assume drink leads to attitude
- Sue pops out to think
- Expect to be affected by drink
- Imagine having drink with model
- Matter for reflection: sit and think
- Fancy duck followed by seconds in endless meal
- Assume son finished model
- Imagine drink with model!
- Guess attitude will be evident after drink
- Imagine meal mostly containing fat?
Buddy explains!

The straight part
We know that "Imagine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case imagine = suppose.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 SUPPOSE mean?
SUPPOSE verb- To take for granted; to conclude, with less than absolute supporting data; to believe.
- To theorize or hypothesize.
- To imagine; to believe; to receive as true.
- To require to exist or to be true; to imply by the laws of thought or of nature.
- To put by fraud in the place of another.