Cryptic crossword clue
This compares different sources of interference 12

The most common and most likely answer to this crossword clue is the 12 letter word ATMOSPHERICS

I've seen this crossword clue in The Guardian
A
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Buddy explains!

The straight part
We know that "sources of interference" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sources of interference = atmospherics.
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 ATMOSPHERICS mean?

ATMOSPHERICS noun
  1. Radio interference caused by pulses of electromagnetic radiation in the atmosphere as the result of lightning and other events (both natural and man-made)

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