Unidentified male smashed in head (8)
I believe the answer is:
nameless
'unidentified' is the definition.
('nameless' can be a synonym of 'unidentified')
'male smashed in head' is the wordplay.
'smashed' indicates an anagram.
'in' indicates putting letters inside.
'head' becomes 'ness' (ness is a headland**).
'male' anagrammed gives 'amel'.
'amel' going within 'ness' is 'NAMELESS'.
(Other definitions for nameless that I've seen before include "Lacking means of identification" , "Salesmen lacking identity" , "Untitled" , "Unidentified" , "like the guy in the spaghetti movies?" .)