Primitive man brooking no delay (6)
I believe the answer is:
urgent
'brooking no delay' is the definition.
I can't judge whether this definition defines the answer.
'primitive man' is the wordplay.
'primitive' becomes 'ur' (prefix meaning the earliest or original).
'man' becomes 'gent' (gent is a kind of man).
'ur'+'gent'='URGENT'
Can you help me to learn more?
(Other definitions for urgent that I've seen before include "High priority" , "Requiring immediate attention" , "Critical" , "Earnest, insistent" , "demanding speedy action" .)