Say drain has front missing (5)
I believe the answer is:
utter
'say' is the definition.
(to utter something is to speak or say it)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for utter that I've seen before include "Complete; absolute" , "Absolute - say" , "Dead" , "Say the words" , "Pure" .)