Wild rage displayed by an American President (6)
I believe the answer is:
reagan
'american president' is the definition.
(I've seen this before)
'wild rage displayed by an' is the wordplay.
'wild' indicates anagramming the letters.
'displayed by' means one lot of letters go next to another.
'rage' anagrammed gives 'reag'.
'reag'+'an'='REAGAN'
(Other definitions for reagan that I've seen before include "40th US president, Ronald" , "40th president of the United States" , "Ronald ..., ex-president of USA" , "40th US president, d. 2004" , "head of state" .)