Stormy sea, for me, is terrifying (8)
I believe the answer is:
fearsome
'is terrifying' is the definition.
(I've seen this before)
'stormy sea for me' is the wordplay.
'stormy' indicates an anagram.
'sea'+'for'='seafor'
'seafor' anagrammed gives 'fearso'.
'fearso'+'me'='FEARSOME'
(Other definitions for fearsome that I've seen before include "Formidable" , "Horrendous" , "Of frightening appearance" , "Frightening, terrible" , "Frightful" .)