Girlfriend holding note, about to go off (8)
I believe the answer is:
detonate
'go off' is the definition.
(I know that go off can be written as detonate)
'girlfriend holding note about' is the wordplay.
'girlfriend' becomes 'date' (date can mean someone you are dating).
'holding' means one lot of letters goes inside another.
'about' indicates anagramming the letters.
'note' anagrammed gives 'eton'.
'date' placed around 'eton' is 'DETONATE'.
'to' is the link.
(Other definitions for detonate that I've seen before include "Blow up, explode" , "go off with a bang" , "Set off explosive device" , "Start 15 [EXPLOSION]" , "Trigger" .)