The most common and most likely answer to this crossword clue is the 4 letter word DECK
I've seen this crossword clue in The Guardian
D
E
C
K
More clues leading to the result DECK
Buddy explains!

The straight part
We know that "Pack/ornament" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pack/ornament = deck.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 DECK mean?
DECK noun- Any raised flat surface that can be walked on: a balcony; a porch; a raised patio; a flat rooftop.
- The floorlike covering of the horizontal sections, or compartments, of a ship. Small vessels have only one deck; larger ships have two or three decks.
- A main aeroplane surface, especially of a biplane or multiplane.
- A pack or set of playing cards.
- (by extension) A set of cards owned by each individual player and from which they draw when playing.
- A set of slides for a presentation.
- A heap or store.
- A folded paper used for distributing illicit drugs.
- The floor.
- To furnish with a deck, as a vessel.
- To knock someone to the floor, especially with a single punch.
- To cause a player to run out of cards to draw and usually lose the game as a result.
- (sometimes with out) To dress (someone) up, to clothe with more than ordinary elegance
- (sometimes with out) To decorate (something).
- To cover; to overspread.