Prince, idiot to break down (5)
I believe the answer is:
parse
'break down' is the definition.
(parsing is a kind of breaking down)
'prince idiot' is the wordplay.
'prince' becomes 'p' (abbreviation).
'idiot' becomes 'arse' (both are insults).
'p'+'arse'='PARSE'
'to' acts as a link.
(Other definitions for parse that I've seen before include "Resolve (a sentence) into its constituent parts" , "analyse this, for instance" , "Spear (anag.); analyse" , "Analyse syntactically" , "Work out clue" .)