The most common and most likely answer to this crossword clue is the 3 plus 4 plus 3 plus 5 letter word THE SAME OLD STORY
I've seen this crossword clue in The Times
T
H
E
S
A
M
E
O
L
D
S
T
O
R
Y
More clues leading to the result THE SAME OLD STORY
Buddy explains!
The straight part
We know that "we've heard that so many times before" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case we've heard that so many times before = the same old story.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.