Destroyed a kingdom in the end, possibly (5)
I believe the answer is:
nuked
'destroyed' is the definition.
The answer and definition can be both related to competing as well as being past participle verbs.
Maybe there's an association between them I don't understand?
'a kingdom in the end possibly' is the wordplay.
'a kingdom' becomes 'uk' (UK is an example).
'in' is an insertion indicator.
'possibly' indicates an anagram.
'end' anagrammed gives 'ned'.
'uk' placed inside 'ned' is 'NUKED'.
Can you help me to learn more?
(Other definitions for nuked that I've seen before include "Used bombs" , "zapped into oblivion?" .)