Humane reason to buy presents (9)
I believe the answer is:
forgiving
'humane' is the definition.
(thesaurus)
'to buy presents' is the wordplay.
'to' becomes 'for'.
'buy presents' becomes 'giving' (I can't explain this - if you can you should believe this answer much more).
'for'+'giving'='FORGIVING'
'reason' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for forgiving that I've seen before include "Lenient" , "Ready to excuse" , "Excusing" , "Pardoning" , "Giving pardon" .)