Soldiers and police surrounding king (5)
I believe the answer is:
corps
'soldiers' is the definition.
(a group of soldiers)
'police surrounding king' is the wordplay.
'police' becomes 'cops' (I've seen this before).
'surrounding' indicates putting letters inside.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'cops' going around 'r' is 'CORPS'.
'and' is the link.
(Other definitions for corps that I've seen before include "Army grouping" , "Army unit" , "Part of an army" , "Military body" , "ballet group" .)