The most common and most likely answer to this crossword clue is the 10 letter word HYPHENATED
I've seen this crossword clue in The Times
H
Y
P
H
E
N
A
T
E
D
More clues leading to the result HYPHENATED
Buddy explains!

The straight part
We know that "Like do-gooder, say" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case like do-gooder, say = hyphenated.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 HYPHENATED mean?
HYPHENATED verb- To break a word at the end of a line according to the hyphenation rules by adding a hyphen on the end of the line.
- To join words or syllables with a hyphen.
- Written with a hyphen.
- Of a person, considered to have more than one nationality or ethnicity (such as French-Canadian, Afro-Argentine, etc.).