It lasts activist involved in conditions affecting human life (5,10)
I believe the answer is:
vital statistics
'in conditions affecting human life' is the definition.
I can't tell whether this definition defines the answer.
'it lasts activist involved' is the wordplay.
'involved' is an anagram indicator (involved can mean confusing or complex).
'it'+'lasts'+'activist'='itlastsactivist'
'itlastsactivist' with letters rearranged gives 'VITAL STATISTICS'.
Can you help me to learn more?
(Other definitions for vital statistics that I've seen before include "Quantitative data" , "Miss World will have supplied?" , "Important figures" , "that are expanded by a corporation" .)