Happen to have the duplicate keys in our possession (5)
I believe the answer is:
occur
'happen' is the definition.
(I know that happen is a more specific form of happen)
'the duplicate keys in our possession' is the wordplay.
I cannot really understand how this works, but
'keys' could be 'cc' (two C's - as in the musical key of C) and 'cc' is located in the answer.
The remaining letters 'our' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'to have' acts as a link.
Can you help me to learn more?
(Other definitions for occur that I've seen before include "Befall" , "appear" , "crop up" , "found" , "Go on" .)