The most common and most likely answer to this crossword clue is the 9 letter word DISRUPTED
I've seen this crossword clue in The Guardian
D
I
S
R
U
P
T
E
D
Buddy explains!

The straight part
We know that "Interfered with" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case interfered with = disrupted.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does DISRUPTED mean?
DISRUPTED verb- To throw into confusion or disorder.
- To interrupt or impede.
- To improve a product or service in ways that displace an established one and surprise the market.
- Subject to disruption.