Require extremely large and pointy implement (6)
I believe the answer is:
needle
'pointy implement' is the definition.
(needles are pointy)
'require extremely large' is the wordplay.
'require' becomes 'need' (synonyms).
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'large' with its centre removed is 'le'.
'need'+'le'='NEEDLE'
'and' is the link.
(Other definitions for needle that I've seen before include "counter" , "Unnecessary" , "Implement for knitting and sewing" , "joint" , "Sewer's implement" .)