The most common and most likely answer to this crossword clue is the 4 plus 3 letter word NULL SET
I've seen this crossword clue in The Guardian
N
U
L
L
S
E
T
More clues leading to the result NULL SET
- Former teachers include lecturer breaking into university? There’s nothing in that
- Nutshell rotten, not hard – one is empty
- Sell nonsense in head, there’s nothing in it
- There’s nothing in it for a mathematician
- Sell fake stone rings — there’s nothing in it
- Cuckoo nest's full inside — on becoming footloose it's empty
- In nutshell, without hydrogen supply, there's something that has nothing
- Nutshell not hard, easily broken — it's empty
- After editing, tell Sun it’s valueless
Buddy explains!
The straight part
We know that "there’s nothing in it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case there’s nothing in it = null set.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.