While fools react, I have to be brief and original! (8)
I believe the answer is:
creative
'original' is the definition.
(associated in meaning)
'while fools react i have to be brief' is the wordplay.
I cannot quite see how this works, but
an anagram of 'react' is 'creat' which is present in the answer.
'i' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for creative that I've seen before include "Using the imagination" , "Imaginative, artistic" , "Full of ideas" , "Inventive, artistic" , "Artistic, able to make new things" .)