Say or do again (6)
I believe this is a double definition.
'say' is the first definition.
(thesaurus)
'do again' is the second definition.
(I've seen this in another clue)
(Other definitions for repeat that I've seen before include "Say or perform again" , "Say again, or burp" , "Ditto" , "Give another performance" , "old TV show" .)
'say or do again' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for iterate that I've seen before include "Repeat, state again" , "Recapitulate" , "Say again, repeat" , "Utter or perform repeatedly" , "State repeatedly, say again" .)