The most common and most likely answer to this crossword clue is the 9 letter word SENSITIVE
I've seen this crossword clue in Financial Times
S
E
N
S
I
T
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V
E
More clues leading to the result SENSITIVE
- Even so, to begin with it is surprisingly controversial
- Easily upset, it is even beginning to snow afresh
- Delicate appeal six took up in hearing?
- Diplomatic visit seen to be controversial
- Diplomatic invitees dance following start of soir?e
- School's invitees becoming problematic
- Diplomatic visit seen to be in error
- Touchy lunatic ties vines
Buddy explains!

The straight part
We know that "controversial" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case controversial = sensitive.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 SENSITIVE mean?
SENSITIVE noun- A person with a paranormal sensitivity to something that most cannot perceive.
- Having the faculty of sensation; pertaining to the senses.
- Responsive to stimuli.
- (of a person) Easily offended, upset or hurt.
- (of an issue, topic, etc.) Capable of offending, upsetting or hurting.
- Meant to be concealed or kept secret.
- (of an instrument) Accurate; able to register small changes in some property.
- Having paranormal abilities that can be controlled through mesmerism.