One who gives, let's assume, to some of the poor (5)
I believe the answer is:
donor
'one who gives' is the definition.
(I've seen this before)
'let's assume to some of the poor' is the wordplay.
'let's assume' becomes 'don' (I can't explain this - if you can you should believe this answer much more).
'to some of' indicates the central letters (I've seen 'some' mean this).
'the poor' becomes 'notasfortunate' (I've seen this in another clue).
The middle letters of 'notasfortunate' are 'or'.
'don'+'or'='DONOR'
Can you help me to learn more?
(Other definitions for donor that I've seen before include "Someone providing" , "One who gives, perhaps blood" , "blessed person, relatively" , "Almsgiver, benefactor" , "Philanthropist" .)