Terrible event, perhaps -- in fact good, strangely (3,2,3)
I believe the answer is:
act of god
'terrible event perhaps' is the definition.
(eg a natural disaster)
'fact good strangely' is the wordplay.
'strangely' indicates anagramming the letters.
'fact'+'good'='factgood'
'factgood' anagrammed gives 'ACT OF GOD'.
'in' is the link.
(Other definitions for act of god that I've seen before include "Event outside human control" , "Unforeseeable accident" , "Divine performance" , "Uncontrollable natural event -dictated by deity?" , "naturally a disaster?" .)