Entice police chief initially developing freedom in lines (6,7)
I believe the answer is:
poetic licence
'freedom in lines' is the definition.
(freedom to change real details for poetic effect)
'entice police chief initially developing' is the wordplay.
'initially' says to take the initial letters.
'developing' indicates an anagram.
The initial letter of 'chief' is 'c'.
'entice'+'police'+'c'='enticepolicec'
'enticepolicec' is an anagram of 'POETIC LICENCE'.
(Other definitions for poetic licence that I've seen before include "Creative freedom for writer or artist" , "A taking of liberties" , "Departing from accuracy for artistic effect" , "Bending the rules for artistic effect" , "Excuse for rule-breaking" .)