Thomas, noted for a generalised philosophy (5)
I believe the answer is:
ethos
'philosophy' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ethos that I've seen before include "Characteristic spirit (of, eg, a culture)" , "Distinctive principles of an era, group, etc" , "Moral significance" , "Cultural spirit" , "Characteristic spirit, of a culture say" .)