What the storm did, that upset Edgar (5)
I believe the answer is:
raged
'what the storm did' is the definition.
I can't judge whether this definition defines the answer.
'upset edgar' is the wordplay.
'upset' indicates anagramming the letters.
'edgar' is an anagram of 'RAGED'.
'that' is the link.
Can you help me to learn more?
(Other definitions for raged that I've seen before include "Behaved violently" , "was having fits" , "Flipped one's lid" , "Showed violent anger" , "Spoke violently" .)