Detective policy leading to stretch (8)
I believe the answer is:
distance
'stretch' is the definition.
(thesaurus)
'detective policy leading' is the wordplay.
'detective' becomes 'di' (Detective Inspector abbreviation).
'policy' becomes 'stance' (I've seen this before).
'leading' says to put letters next to each other.
'di'+'stance'='DISTANCE'
'to' is the link.
(Other definitions for distance that I've seen before include "standoffishness" , "Space between things" , "What's kept in reserve" , "to make big winning margin" , "Space between two places" .)