The most common and most likely answer to this crossword clue is the 8 letter word MARCHING
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More clues leading to the result MARCHING
Buddy explains!

The straight part
We know that "On parade" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case on parade = marching.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 MARCHING mean?
MARCHING verb- To walk with long, regular strides, as a soldier does.
- To cause someone to walk somewhere.
- To go to war; to make military advances.
- To make steady progress.
- To have common borders or frontiers
- An action described by the verb "to march".
- That marches.
- Placed or situated in a line or lines, reminiscent or evocative of marching soldiers.