The most common and most likely answer to this crossword clue is the 3 plus 3 plus 5 plus 4 letter word PUT THE CLOCK BACK
I've seen this crossword clue in The Daily Telegraph
P
U
T
T
H
E
C
L
O
C
K
B
A
C
K
Buddy explains!
The straight part
We know that "take a retrograde step" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case take a retrograde step = put the clock back.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.