The most common and most likely answer to this crossword clue is the 15 letter word PERSONALISATION
I've seen this crossword clue in The Guardian
P
E
R
S
O
N
A
L
I
S
A
T
I
O
N
Buddy explains!

The straight part
We know that "Tailored configuration/it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tailored configuration/it = personalisation.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.
Crossword Answer definitions
PERSONALISATION noun- The act of personalizing something, or adapting it for somebody's needs or tastes.
- The act of personifying; personification.