Pass by one with Sherlock Holmes initially (6)
I believe the answer is:
Here is my best explanation:
'pass' is the definition.
'by one with sherlock holmes initially' is the subsidiary indication.
'by' becomes 'per' (**).
'one with' becomes 'i' (I've seen this in other clues).
'initially' indicates taking the first letters.
The first letters of 'sherlock holmes' is 'sh'.
(Other definitions for perish that I've seen before include "Die - rot", "Die; decay", "come to grief", "Deteriorate, rot", "Rot, die", "Suffer complete ruin or destruction", "Rot or suffer untimely death", "Expire", "fall" and "Lose one's life".)