Cohort that gets on together (3,5)
I believe the answer is:
age group
'cohort' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for age group that I've seen before include "teenagers?" , "Cohort" , "Old folk maybe" , "Demographic bracket" , "People of the same generation" .)