Shocking, though seemingly quite proper to a fathead (9)
I believe the answer is:
frightful
'shocking' is the definition.
(thesaurus)
'proper to a fathead' is the wordplay.
'proper' becomes 'rightful' (I've seen this before).
'to a' says to put letters next to each other (I've seen this in other clues).
'fathead' becomes 'f' (head letter of 'fat').
'rightful' put after 'f' is 'FRIGHTFUL'.
'though seemingly quite' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for frightful that I've seen before include "from hell" , "ugly" , "Appalling" , "very bad" , "horrible" .)