The right sort of blonde is impetuous! (4)
I believe the answer is:
rash
'impetuous' is the definition.
(I've seen this before)
'the right sort of blonde' is the wordplay.
I cannot quite see how this works, but
'right' could be 'r' (common abbreviation) and 'r' is present in the answer.
'blonde' could be 'ash' (I've seen this before) and 'ash' is located in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'is' acts as a link.
Can you help me to learn more?
(Other definitions for rash that I've seen before include "complaint" , "Hives" , "sign of irritation?" , "Skin redness" , "Hasty; series of things" .)