Over-confidence? Core feature with endless peril (6)
I believe the answer is:
hubris
'over-confidence?' is the definition.
(I've seen this before)
'core feature with endless peril' is the wordplay.
'core feature with' becomes 'hub' (I can't justify this - if you can you should believe this answer much more).
'endless' means to remove the last letter.
'peril' becomes 'risk' (synonyms).
'risk' with its last letter removed is 'ris'.
'hub'+'ris'='HUBRIS'
Can you help me to learn more?
(Other definitions for hubris that I've seen before include "feeling of superiority" , "Overbearing pride or self-confidence" , "show of arrogance" , "Arrogance or over-confidence" , "Arrogant pride or presumption" .)