New knight assigned powers to use one’s full potential (6,4,5)
I believe the answer is:
spread ones wings
'use one's full potential' is the definition.
(to spread your wings is to use your full potential)
'new knight assigned powers' is the wordplay.
'new' indicates anagramming the letters.
'knight' becomes 'N' (chess abbreviation).
'n'+'assigned'+'powers'='nassignedpowers'
'nassignedpowers' anagrammed gives 'SPREAD ONES WINGS'.
'to' is the link.
(Other definitions for spread ones wings that I've seen before include "Try something new" , "make full use of one's talents" , "Develop abilities fully" , "as a high-flyer would?" .)