The most common and most likely answer to this crossword clue is the 2 plus 4 letter word SO WHAT
I've seen this crossword clue in The Guardian
S
O
W
H
A
T
More clues leading to the result SO WHAT
- Who cares if pig has cover for head?
- Beastly female given crown? I couldn't care less!
- I'm not interested in female item of clothing
- Headgear for pig? It’s of no consequence
- Female on top of sombrero, perhaps? Never mind!
- Broadcast Derby? Big deal!
- I don’t care who’s at fault
- Broadcast endless spite; see if I care!
- Brooded over Doctor Who’s words of contempt
- Broadcast by deerstalker who cares?
Buddy explains!
The straight part
We know that "Big deal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case big deal = so what.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.