Extremely sarcastic youth leader with the mowing implement (6)
I believe the answer is:
scythe
'mowing implement' is the definition.
(I've seen this before)
'extremely sarcastic youth leader with the' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'youth leader' becomes 'y' (I've seen this in other clues).
'with' says to put letters next to each other.
'sarcastic' with its middle removed is 'sc'.
'sc'+'y'+'the'='SCYTHE'
(Other definitions for scythe that I've seen before include "what the reaper holds" , "Mowing blade" , "Manual hay-cutter wielded with both hands" , "Tool for cutting grass with blade on long pole" , "Old-fashioned hand-held hay mower" .)