For eccentric, older, a difficult experience (6)
I believe the answer is:
ordeal
'difficult experience' is the definition.
(I've seen this in another clue)
'for eccentric older a' is the wordplay.
'older a' anagrams to 'ORDEAL'.
Though, I'm unsure how this is indicated.
Can you help me to learn more?
(Other definitions for ordeal that I've seen before include "Loader (anag.)" , "Torment" , "One may be difficult" , "Disturbing experience" , "Difficult experience that tests endurance" .)