Damn! This is awfully unpredictable (3,3,4)
I believe the answer is:
hit and miss
'unpredictable' is the definition.
'damn this is awfully' is the wordplay.
'awfully' is an anagram indicator.
'damn'+'this'+'is'='damnthisis'
'damnthisis' is an anagram of 'HIT-AND-MISS'.
(Other definitions for hit and miss that I've seen before include "with no pattern" , "Haphazard" , "with no guarantee of success" , "Random" , "Mixed" .)