Breaks in speech for king (3)
I believe the answer is:
rex
'for king' is the definition.
('king' in Latin)
'breaks in speech' is the wordplay.
'breaks' becomes 'wrecks'.
'in speech' indicates a 'sounds like' (homophone) clue.
'wrecks' sounds like 'REX'.
(Other definitions for rex that I've seen before include "King (L.)" , "King (Latin); cat breed" , "Dog's name; king" , "Oedipus - -" , "One in the palace" .)