For a fathead, a proper scare (6)
I believe the answer is:
fright
'scare' is the definition.
(I know that fright can be written as fright)
'for a fathead a proper' is the wordplay.
I cannot quite understand how this works, but
'fathead' could be 'f' (head letter of 'fat') and 'f' is found within the answer.
'proper' could be 'right' (associated in meaning) and 'right' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for fright that I've seen before include "Shock, sudden alarm" , "Terror" , "Sudden feeling of fear" , "Start" , "Panic" .)