The most common and most likely answer to this crossword clue is the 5 letter word TWAIN
I've seen this crossword clue in The Times
T
W
A
I
N
More clues leading to the result TWAIN
- Pair including a novelist
- Writer Mark’s time alongside farm cart
- Couple, the first on the wagon
- Writer’s counterpart receiving top mark
- Double to host a US writer
- Two tons taken by old farm wagon
- One author, or two
- An American writer or two
- Home on time, starts to woo au pair
- Old couple needing time on the wagon
Buddy explains!

The straight part
We know that "Two" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case two = twain.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 TWAIN mean?
TWAIN noun- Pair, couple
- Twofold
- Two
- To part in twain; divide; sunder.