Just happened to be wicked (6)
I believe the answer is:
befell
'just happened' is the definition.
'befell' can be an answer for 'happened' (I've seen this before). I am unsure of the 'just' bit.
'be wicked' is the wordplay.
'wicked' becomes 'fell' (I am not sure about this - if you are sure you should believe this answer much more).
'be'+'fell'='BEFELL'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for befell that I've seen before include "Happened to (someone)" , "Happened, came to pass" .)