Very sensitive street cop is rattled (3-6)
I believe the answer is:
top-secret
'very sensitive' is the definition.
(top secret means very sensitive or classified)
'street cop is rattled' is the wordplay.
'is rattled' is an anagram indicator.
'street'+'cop'='streetcop'
'streetcop' anagrammed gives 'TOP-SECRET'.
(Other definitions for top-secret that I've seen before include "Highly confidential" , "Highly restricted (information)" , "Highest classified (information)" , "Highly classified" , "Very hush-hush" .)