The most common and most likely answer to this crossword clue is the 6 letter word DOTTED
I've seen this crossword clue in Financial Times
D
O
T
T
E
D
Buddy explains!
The straight part
We know that "in the form of ellipses" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the form of ellipses = dotted.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 DOTTED mean?
DOTTED verb- To cover with small spots (of some liquid).
- To add a dot (the symbol) or dots to.
- To mark by means of dots or small spots.
- To mark or diversify with small detached objects.
- To punch (a person).
- (of a line) Made up of a series of dots.
- (usually computing) That contains dots.
- (of notes and rests) With a dot after, increasing the value of the duration by half of the basic note.
- Covered with irregularly scattered objects.