The most common and most likely answer to this crossword clue is the 8 plus 5 letter word AMERICAN DREAM
I've seen this crossword clue in The Daily Telegraph
A
M
E
R
I
C
A
N
D
R
E
A
M
More clues leading to the result AMERICAN DREAM
- Cameramen raid compound in pursuit of happiness
- Reformed madam in career that shows anything is possible
- Fantastic cinema drama about the Queen – it suggests all can gain fame and fortune
- A man taking boy hostage, possibly armed, becomes a national obsession
- Nation’s ideal Kentucky whiskey, possibly containing Ecstasy
- For instance, James Stewart fantasy ‘It’s a Wonderful Life’
Buddy explains!
The straight part
We know that "Nation’s ideal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nation’s ideal = american dream.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.