Getting new order street cop is not to be mentioned (3,6)
I believe the answer is:
top secret
'not to be mentioned' is the definition.
I can't judge whether this defines the answer.
'getting new order street cop' is the wordplay.
'getting new order' indicates anagramming the letters.
'street'+'cop'='streetcop'
'streetcop' is an anagram of 'TOP-SECRET'.
'is' is the link.
Can you help me to learn more?
(Other definitions for top secret that I've seen before include "Highly confidential" , "Well-hidden" , "Like highly guarded information" , "Highly classified" , "Of the highest security classification" .)