People pass on - one's hidden inside (8)
I believe the answer is:
colonise
'people' is the definition.
(colonise can mean to people or populate a colony)
'pass on one's hidden inside' is the wordplay.
'pass' becomes 'cole' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'one's' becomes 'i's' (Roman numeral).
'hidden inside' indicates putting letters inside.
'on'+'is'='onis'
'cole' going around 'onis' is 'COLONISE'.
Can you help me to learn more?
(Other definitions for colonise that I've seen before include "Form a settlement in a foreign country" , "Populate, settle" , "Establish a state in conquered territory" .)