Lamented ignorant broadcast? (4)
I believe the answer is:
rued
'lamented' is the definition.
'ignorant broadcast?' is the wordplay.
'ignorant' becomes 'rude'.
'broadcast?' indicates a 'sounds like' (homophone) clue (I've seen 'broadcast' mean this (how the word might sound on the radio or TV)).
'rude' is a homophone of 'RUED'.
(Other definitions for rued that I've seen before include "'Regretted, repented (4)'" , "Was contrite about" , "was remorseful" , "Bitterly regretted" , "Was sorry" .)