I'm sorry to say . . . (11)
'i'm sorry to say' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for alas that I've seen before include "Expression of grief or misfortune" , "Proper, respectable" , "Oh dear!" , "Sad expression" , "More's the pity" .)
(Another definition for regrettably that I've seen is " I'm afraid".)