Noble king, fantastic thing (6)
I believe the answer is:
knight
'noble' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'king fantastic thing' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'fantastic' is an anagram indicator (a fantastic or improbable ordering of the letters).
'thing' anagrammed gives 'night'.
'k'+'night'='KNIGHT'
Can you help me to learn more?
(Other definitions for knight that I've seen before include "rider looking for adventure?" , "Rank below baronet" , "Dubbed chessman?" , "He was trained in arms and chivalry in olden days" , "Titled man - chessman" .)