Shoot down extremely sick pitcher (6)
I believe the answer is:
skewer
'shoot down' is the definition.
Although both the answer and definition are verbs in their base form, I can't see how they can define each other.
'extremely sick pitcher' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'pitcher' becomes 'ewer' (synonyms).
'sick' with its middle taken out is 'sk'.
'sk'+'ewer'='SKEWER'
Can you help me to learn more?
(Other definitions for skewer that I've seen before include "Pin for meat etc" , "Food spike" , "barbecue implement?" , "Metal stick (that's more awry?)" , "Spike on which kebab is cooked" .)