The most common and most likely answer to this crossword clue is the 6 letter word SLO-MO
I've seen this crossword clue in The Times
S
L
O
-
M
O
Buddy explains!

The straight part
We know that "Reduced pace" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reduced pace = slo-mo.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 SLO-MO mean?
SLO-MO noun- A technique of film, photography and video to stretch time and allow visibility of things normally happening too fast to be conveniently examined.