Vehicle in ditch - traffic is stuck at the side DUMP TRUCK
Ditch = DUMP, not sure about the rest, maybe traffic = TR, + stuck at the side = UCK. Poor clue if that's right.
Olympic athliete has energy in reserve OWENS
Has = OWNS with E for energy inreserve. Black American Jesse Owens won 4 Golds at the Berlin Olympics, much to Hitler's displeasure.
Chairman Mao in the shade CHINESE RED
Chairman Mao was a CHINESE RED (communist) which is a shade or colour.