Give a name to unopened flower that's coming up (3)
I believe the answer is:
dub
'give a name' is the definition.
(I've seen this in another clue)
'unopened flower that's coming up' is the wordplay.
'unopened flower' becomes 'bud' (I've seen this before).
'that's coming up' says the letters should be written backwards (in a down clue, letters go up).
'bud' back-to-front is 'DUB'.
'to' is the link.
(Other definitions for dub that I've seen before include "Give a name to" , "Copy to tape or disc" , "Reggae" , "Label, name" , "Add a soundtrack in a different language" .)