The most common and most likely answer to this crossword clue is the 5 letter word NIMBY
I've seen this crossword clue in The Guardian
N
I
M
B
Y
Buddy explains!

The straight part
We know that "a selfish sort?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a selfish sort? = nimby.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 NIMBY mean?
NIMBY noun- (usually derogatory) Someone who objects to the building of an undesirable structure in their neighborhood, especially in public policy debate.
- Not wanting to have to deal with unpleasant or distasteful things near them.