Fear of an ancient deity, I see (5)
I believe the answer is:
panic
'fear' is the definition.
(I know that panic is a type of fear)
'an ancient deity i see' is the wordplay.
'an ancient deity' becomes 'pan' (Pan is an example. I am not sure about the 'ancient' bit.).
'see' becomes 'C' (the word for the letter, according to Chambers).
'pan'+'i'+'c'='PANIC'
'of' is the link.
Can you help me to learn more?
(Other definitions for panic that I've seen before include "Losing one's head" , "Frantic fear" , "Lose the head, yield to fear" , "Alarm - terror" , "Frantic fright" .)