Hide piece of fiction - it's despicable
I believe the answer is:
lie low
'hide' is the definition.
(lying low is a kind of hiding)
'piece of fiction it's despicable' is the wordplay.
'piece of fiction' becomes 'lie' (I've seen this before).
'it's despicable' becomes 'low' ('low' can be a synonym of 'despicable').
'lie'+'low'='LIE LOW'
(Other definitions for lie low that I've seen before include "Wait for a favourable opportunity" , "Remain unobtrusive - in prone posture?" , "Absent oneself from social contact (for a period)" , "Conceal oneself, don't make intentions known" , "Conceal oneself, don't be conspicuous" .)