The most common and most likely answer to this crossword clue is the 13 letter word CARPETBAGGERS
I've seen this crossword clue in The Guardian
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More clues leading to the result CARPETBAGGERS
Buddy explains!
The straight part
We know that "Opportunists" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case opportunists = carpetbaggers.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 CARPETBAGGERS mean?
CARPETBAGGERS noun- (history) An immigrant from the Northern to the Southern States after the American Civil War of 1861–5, especially one who went South to gain political influence.
- (by extension) One who comes to a place or organisation with which they have no previous connection with the sole or primary aim of personal gain, especially political or financial gain.