Don’t interfere with holiday busy person cut short (5,2)
I believe the answer is:
leave be
'don't interfere' is the definition.
'with holiday busy person cut short' is the wordplay.
'with' says to put letters next to each other.
'holiday' becomes 'leave' (I've seen this before).
'busy person' becomes 'bee' (I've seen this in other clues).
'cut short' means to remove the last letter.
'bee' with its last letter removed is 'be'.
'leave' put next to 'be' is 'LEAVE BE'.
(Other definitions for leave be that I've seen before include "Refrain from disturbing (someone)" , "Let remain undisturbed" .)