The most common and most likely answer to this crossword clue is the 8 letter word CIRCULAR
I've seen this crossword clue in The Daily Telegraph
C
I
R
C
U
L
A
R
Buddy explains!
The straight part
We know that "Round/letter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case round/letter = circular.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 CIRCULAR mean?
CIRCULAR noun- Short for circular letter.
- A sleeveless cloak cut from a circular pattern.
- A shuttle bus with a circular route.
- To distribute circulars to or at.
- To extend in a circular direction.
- Of or relating to a circle.
- In the shape of, or moving in a circle.
- Circuitous or roundabout.
- Referring back to itself, so as to prevent computation or comprehension; infinitely recursive.
- Distributed to a large number of persons.
- Perfect; complete.
- Adhering to a fixed circle of legends; cyclic; hence, mean; inferior.
- That which flies, as a bird or insect.
- A machine that flies.
- An airplane pilot.
- A person who travels by airplane.
- A leaflet, often for advertising.
- The part of a spinning machine that twists the thread as it takes it to and winds it on the bobbin
- An arch that connects a flying buttress into the structure it supports.
- (acrobatics, cheerleading, synchronized swimming) The person who is lifted and/or thrown by another person or persons.
- A stray shot away from the group on a target.
- A standard rectangular step of a staircase (as opposed to a winder).
- A female kangaroo; a roo; a doe; a jill.
- A leap or jump.
- A risky investment or other venture.