The most common and most likely answer to this crossword clue is the 4 plus 2 plus 2 plus 7 letter word LAND OF MY FATHERS
I've seen this crossword clue in The Daily Telegraph
L
A
N
D
O
F
M
Y
F
A
T
H
E
R
S
More clues leading to the result LAND OF MY FATHERS
Buddy explains!

The straight part
We know that "a patriotic song" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a patriotic song = land of my fathers.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.