The most common and most likely answer to this crossword clue is the 7 letter word SPARTAN
I've seen this crossword clue in Financial Times
S
P
A
R
T
A
N
More clues leading to the result SPARTAN
- Excitedly ran past Leonidas for example
- Old Greek box, brown
- Hardy box bark
- Fight nationalist who's rising, austere
- Society role played by an austere old Greek
- Greek once affected by austerity?
- Spare part installed by artisan after losing first four
- Severe criminal charges mounting over nationalist uprising
- Bleak role in hospital
- Having no fun from creativity in one’s lifetime
Buddy explains!

The straight part
We know that "Severe" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case severe = spartan.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 SPARTAN mean?
SPARTAN adjective- Austere, frugal, characterized by self-denial.
- Resolute in the face of danger or adversity.
- Lacking in decoration and luxury.