Manly youth leader carrying chest? Nonsense (8)
I believe the answer is:
malarkey
'nonsense' is the definition.
(I've seen this before)
'manly youth leader carrying chest?' is the wordplay.
'manly' becomes 'male' (synonyms).
'youth leader' becomes 'y' (I've seen this in other clues).
'carrying' is an insertion indicator.
'chest?' becomes 'ark' (historical term for a chest).
'male'+'y'='maley'
'maley' going around 'ark' is 'MALARKEY'.
(Other definitions for malarkey that I've seen before include "Nonsensical stuff" , "Absurd talk" , "Slangy humbug or nonsense - sounds like Irish name" , "Cock" , "Idle words" .)