During Christmas, to donate, give an extinct mammal (8)
I believe the answer is:
mastodon
'an extinct mammal' is the definition.
'during christmas to donate' is the wordplay.
'during' indicates a hidden word.
'MASTODON' is hidden within 'christmas to donate'.
'give' is the link.
(Other definitions for mastodon that I've seen before include "Extinct elephant ancestor" , "dead hairy beast" , "giant from the past" , "Big beast" , "Huge animal" .)