Group of animals surrounding old king (5)
I believe the answer is:
herod
'king' is the definition.
(I know that Herod is a king)
'group of animals surrounding old' is the wordplay.
'group of animals' becomes 'herd' (I've seen this before).
'surrounding' is an insertion indicator.
'old' becomes 'o' (abbreviation).
'herd' enclosing 'o' is 'HEROD'.
(Other definitions for herod that I've seen before include "Massacre-of-Innocents king" , "New Testament king" , "Former king" , "Biblical king of Judea" , "Roman king of Judaea" .)