Bolt secures English king (6)
I believe the answer is:
george
'king' is the definition.
(George is an example)
'bolt secures english' is the wordplay.
'bolt' becomes 'gorge' (both can mean to eat).
'secures' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'gorge' enclosing 'e' is 'GEORGE'.
(Other definitions for george that I've seen before include "Automatic pilot (sl.)" , "one in 3 the 12 30 [DROP the DEAD DONKEY]" , "people swear by" , "Dragon slayer" , "The G in G. B. Shaw" .)