Pat goes off to get the police (7)
I believe the answer is:
gestapo
'police' is the definition.
(Nazi secret police)
'pat goes off to get' is the wordplay.
'pat' becomes 'tap' (synonyms).
'off' is an anagram indicator.
'to get' is an insertion indicator.
'goes' with letters rearranged gives 'geso'.
'tap' put within 'geso' is 'GESTAPO'.
'the' is the link.
(Other definitions for gestapo that I've seen before include "war force" , "Hitler's secret police" , "Postage (anag)" , "Geheime Staatspolizei" , "Nazi Germany's secret state police" .)