One generous in the extreme? (3)
I believe the answer is:
tip
'the extreme?' is the definition.
(thesaurus)
'one generous in' is the wordplay.
'one' becomes 'I' (Roman numeral).
'generous' becomes 'tp' (I can't justify this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'i' placed within 'tp' is 'TIP'.
Can you help me to learn more?
(Other definitions for tip that I've seen before include "End; overbalance" , "Gratuity; rubbish-dump" , "Point; piece of advice" , "Helpful information; end" , "expected by those who wait" .)