Intrude in other people's affairs (6)
I believe the answer is:
meddle
'intrude in other people's affairs' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for meddle that I've seen before include "Interfere or tinker" , "Interfere, butt in" , "Interfere in other's business" , "Interfere in another's business" , "Stick one's oar in" .)