One who keeps a catalogue of lofty notions? (8)
I believe the answer is:
idealist
'one who keeps a catalogue of lofty notions?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'one who keeps a' is the wordplay.
'one' becomes 'i' (Roman numeral).
'who' becomes 'delist' (I can't justify this - if you can you should believe this answer much more).
'keeps' is an insertion indicator (inserted letters are kept inside).
'delist' going around 'a' is 'dealist'.
'i'+'dealist'='IDEALIST'
Can you help me to learn more?
(Other definitions for idealist that I've seen before include "One has high hopes" , "Details I accumulated about person with best intentions" , "philosopher" , "Sail tide (anag.)" , "Seeker after perfection" .)