Eternal pursuit of the happy ending (4,5)
I believe the answer is:
ever after
'the happy ending' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'eternal pursuit' is the wordplay.
'eternal' becomes 'ever' (I've seen this in another clue).
'pursuit' becomes 'after' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ever'+'after'='EVER AFTER'
'of' is the link.
Can you help me to learn more?
(Other definitions for ever after that I've seen before include "for good?" , "from then on, till the end of time" .)