The most common and most likely answer to this crossword clue is the 7 letter word EXOTICA
I've seen this crossword clue in The Times
E
X
O
T
I
C
A
More clues leading to the result EXOTICA
- Former accountant keeping books: one unusual collection
- Ace quote about old times turned up in curious collection
- A quote about farm animal cropping up in strange stuff
- Essentially queasy about toxic compound and strange objects
- Earth gets horrendously toxic article, matter from afar
- ‘Abaci to Xeroxes’: retrospective includes unusual items
- Foreign items and old books need art venue
- Bizarre objects, each full of toxic compound
- “Kiss and Love” in a quote about strange things
- Curios once associated with ears
Buddy explains!

The straight part
We know that "unusual collection" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unusual collection = exotica.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 EXOTICA mean?
EXOTICA noun- A genre of American music from the 1950s, characterized by an evocative musical focus on the islands of the South Pacific.