Philosopher — one in short supply (5)
I believe the answer is:
stoic
This clue might be a double definition.
'philosopher' is the first definition.
(type of ancient philosopher)
'one in short supply' is the second definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for stoic that I've seen before include "Philosopher like Marcus Aurelius" , "the original Zeno?" , "Unflappable type" , "Athenian philosopher" , "One able to endure hardship; philosopher" .)