Nutty type of writer takes in most of Cork (5)
I believe the answer is:
pecan
'nutty type' is the definition.
(I've seen this before)
'writer takes in most of cork' is the wordplay.
'writer' becomes 'pen' (I've seen this before).
'takes in' is an insertion indicator.
'most of cork' becomes 'ca' (I am not sure about this - if you are sure you should believe this answer much more).
'pen' going around 'ca' is 'PECAN'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for pecan that I've seen before include "nut-tree" , "Nut tree of the southern United States and Mexico" , "Walnut-like nut" , "Something like a walnut" , "Species of hickory - edible nut" .)