The most common and most likely answer to this crossword clue is the 7 letter word RUFFLED
I've seen this crossword clue in The Times
R
U
F
F
L
E
D
Buddy explains!

The straight part
We know that "disconcerted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case disconcerted = ruffled.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 RUFFLED mean?
RUFFLED verb- To make a ruffle in; to curl or flute, as an edge of fabric.
- To disturb; especially, to cause to flutter.
- To grow rough, boisterous, or turbulent.
- To become disordered; to play loosely; to flutter.
- To be rough; to jar; to be in contention; hence, to put on airs; to swagger.
- To make into a ruff; to draw or contract into puckers, plaits, or folds; to wrinkle.
- To erect in a ruff, as feathers.
- To beat with the ruff or ruffle, as a drum.
- To throw together in a disorderly manner.
- Having ruffles.
- Puffed up like a bird's feathers.
- Bothered.