The most common and most likely answer to this crossword clue is the 3 plus 7 plus 5 letter word THE BLARNEY STONE
I've seen this crossword clue in The Guardian
T
H
E
B
L
A
R
N
E
Y
S
T
O
N
E
More clues leading to the result THE BLARNEY STONE
Buddy explains!
The straight part
We know that "Is it good to kiss and tell" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case is it good to kiss and tell = the blarney stone.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.