Happens to have taken classic extremes into yours and mine (6)
I believe the answer is:
occurs
'happens' is the definition.
('occur' can be a synonym of 'happen')
'classic extremes into yours and mine' is the wordplay.
'extremes' suggests removing the centre.
'into' indicates putting letters inside.
'yours and mine' becomes 'ours' (I've seen this before).
'classic' with its centre removed is 'cc'.
'cc' inserted inside 'ours' is 'OCCURS'.
'to have taken' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for occurs that I've seen before include "Comes to pass" , "Happens, takes place" , "Crocus (anag)" , "Happens or comes to mind" .)