The most common and most likely answer to this crossword clue is the 10 letter word REQUIESCAT
I've seen this crossword clue in The Guardian
R
E
Q
U
I
E
S
C
A
T
Buddy explains!
The straight part
We know that "This leads in pace" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this leads in pace = requiescat.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.
What does REQUIESCAT mean?
REQUIESCAT noun- A prayer for the peaceful repose of the soul of a dead person