Boss tells a whopper about son’s latest pieces of news (9)
I believe the answer is:
headlines
'pieces of news' is the definition.
'boss tells a whopper about son's latest' is the wordplay.
'boss' becomes 'head' ('head' can be a synonym of 'boss').
'tells a whopper' becomes 'lies'.
'about' is an insertion indicator.
'latest' indicates one should take the final letters.
The final letter of 'son' is 'n'.
'lies' enclosing 'n' is 'lines'.
'head'+'lines'='HEADLINES'
(Other definitions for headlines that I've seen before include "Captions of newspaper articles" , "linked with furrowed brows?" , "News stories" , "is star performer" , "Starts of newspaper articles" .)