See terms in policies stop trickery (3)
I believe the answer is:
spy
'see' is the definition.
(spy can mean to see or observe)
'terms in policies stop trickery' is the wordplay.
'terms in' says to take the final letters (I've seen 'term in' mean this (term can mean the end of something)).
The last letters of 'policies stop trickery' are 'SPY'.
(Other definitions for spy that I've seen before include "One who collects secret information as for government" , "Notice" , "One gathers information surreptitiously" , "Catch sight of" , "Person who secretly collects information as for government" .)