The most common and most likely answer to this crossword clue is the 10 letter word PUBLISHING
I've seen this crossword clue in The Guardian
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More clues leading to the result PUBLISHING
Buddy explains!

The straight part
We know that "perishing alternative" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case perishing alternative = publishing.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 PUBLISHING mean?
PUBLISHING verb- To issue (something, such as printed work) for distribution and/or sale.
- To announce to the public.
- To issue the work of (an author).
- To disseminate (a message) publicly via a newsgroup, forum, blog, etc.
- To issue a medium (e.g. publication).
- To have one's work accepted for a publication.
- (of content) To be made available in a printed publication or other medium.
- To convert data of a Web page to HTML in a local directory and copy it to the Web site on a remote system.
- The industry of publishing, including the production and distribution of books, magazines, web sites, newspapers, etc.
- Something published; a publication.