They represent people a long time since perhaps (8)
I believe the answer is:
agencies
'they represent people a long' is the definition.
The definition suggests an adverb but the answer is not.
'time since perhaps' is the wordplay.
'time' becomes 'age' (an age is a period of time).
'perhaps' indicates an anagram.
'since' is an anagram of 'ncies'.
'age'+'ncies'='AGENCIES'
Can you help me to learn more?
(Other definitions for agencies that I've seen before include "They organise transactions, between advertisers and media perhaps" , "Businesses providing specific services" , "Administrative units of government" , "Service organisations" , "Businesses that serves other businesses" .)