Meddle, intrude (9)
I believe the answer is:
interfere
This clue is a double definition.
'meddle' is the first definition.
(to meddle with something is to interfere with it)
'intrude' is the second definition.
(thesaurus)
(Other definitions for interfere that I've seen before include "Obstruct, pry" , "Stick one's oar in" , "Meddle, butt in" , "Meddle, poke into" , "Poke one's nose in" .)