The most common and most likely answer to this crossword clue is the 6 letter word HECTIC
I've seen this crossword clue in Independent
H
E
C
T
I
C
More clues leading to the result HECTIC
- Man in charge around court is frantically active
- Busy, cite changes in hours, constant
- Very active compound of hydrogen, carbon, iodine etc.
- Delirious from hospital shock treatment and sick inside
- Hello admits shocking treatment — celeb initially furious
- Feverish, hot and bothered etc — I have cold
- Feverish convulsion stopped by shock treatment
- Hector, briefly in charge, became frenzied
- Frenetic hospital psychiatric treatment requires intensive care
- Busy hospital with heads of Intensive Care covering up shock therapy
Buddy explains!

The straight part
We know that "Feverish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case feverish = hectic.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 HECTIC mean?
HECTIC noun- A hectic fever.
- A flush like one produced by such a fever.
- Denoting a type of fever accompanying consumption and similar wasting diseases, characterised by flushed cheeks and dry skin.
- Pertaining to or symptomatic of such a fever.
- Very busy with activity and confusion; feverish.