Nothing’s held in trust if there’s denial (3)
I believe the answer is:
not
'denial' is the definition.
'nothing's held in trust' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'held in' is an insertion indicator.
'trust' becomes 'nt' (I am not sure about this - if you are sure you should believe this answer much more).
'o' placed inside 'nt' is 'NOT'.
'if there's' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for not that I've seen before include "Negation of what follows" , "Word of denial" , "In no way, never" , "Having close-cut hair" , "Word of negation" .)