The most common and most likely answer to this crossword clue is the 7 letter word DRASTIC
I've seen this crossword clue in Financial Times
D
R
A
S
T
I
C
More clues leading to the result DRASTIC
- Radical doctor with a brief fix
- Very strong wine imported by African country
- When upset, it’s in character to get violent
- It’s brought back in The Return of the King, perhaps – must be radical
- Radical art disc playing
- Desperate doctor takes wine cold
- Unpleasant doctor has a staff shortage
- Radical starts to drink red wine cold
- Violent doctor about to consume drink
- Extreme seeing doctor over a small twitch
Buddy explains!

The straight part
We know that "extreme" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case extreme = drastic.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 DRASTIC mean?
DRASTIC noun- A powerful, fast-acting purgative medicine.
- Having a strong or far-reaching effect; extreme, severe.
- Acting rapidly or violently.