The most common and most likely answer to this crossword clue is the 5 letter word ABACK
I've seen this crossword clue in The Times
A
B
A
C
K
More clues leading to the result ABACK
- A player on field impeded by headwind?
- A defender so taken by surprise
- A footballer, perhaps, dismayed to be taken thus?
- A second way to be taken when shocked?
- Pressed to the mast, sailor’s to work ‘ard as drudge
- One sailor and another with no joint is surprised, when taken
- A second taken by surprise
- How you may be taken by surprise
- Some black cab always around, so taken unexpectedly
- One’s shocked when one’s taken this
Buddy explains!

The straight part
We know that "dismayed to be taken thus" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dismayed to be taken thus = aback.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 ABACK mean?
ABACK adverb- Towards the back or rear; backwards.
- In the rear; a distance behind.
- By surprise; startled; dumbfounded. (see usage)
- Backward against the mast; said of the sails when pressed by the wind from the "wrong" (forward) side, or of a ship when its sails are set that way.
- An abacus.