The most common and most likely answer to this crossword clue is the 5 letter word DEMUR
I've seen this crossword clue in The Guardian
D
E
M
U
R
More clues leading to the result DEMUR
- Almost reserved object
- Object that's not quite proper
- Odd newsman raised objection
- Object when strange journalist turns up
- Last European quits modest protest
- Curious journalist raised objection
- To be hesitant is not entirely modest
- Reserved reduced object
- Wayward emu regularly hiding object
- Object reserved briefly
Buddy explains!

The straight part
We know that "protest" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case protest = demur.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 DEMUR mean?
DEMUR noun- Stop; pause; hesitation as to proceeding; suspense of decision or action; scruple.
- To linger; to stay; to tarry
- To delay; to pause; to suspend proceedings or judgment in view of a doubt or difficulty; to hesitate; to put off the determination or conclusion of an affair.
- To scruple or object; to take exception; to oppose; to balk
- To interpose a demurrer.
- To suspend judgment concerning; to doubt of or hesitate about
- To cause delay to; to put off