Poor leaders in his August papers — like every silly season? (7)
'poor' is the definition.
'leaders in his august papers like every silly season?' is the wordplay.
'leaders in' says to take the initial letters.
The initial letters of 'his august papers like every silly season' is 'HAPLESS'.
(Other definitions for hapless that I've seen before include "Pathetic", "Ill-starred", "Unlucky, unfortunate", "Ill-fated", "Piteous".)