Writer represented Nike protecting fellow in small cutter (8)
I believe the answer is:
penknife
'small cutter' is the definition.
(a penknife has a small blade)
'writer represented nike protecting fellow' is the wordplay.
'writer' becomes 'pen' (I've seen this before).
'represented' is an anagram indicator.
'protecting' means one lot of letters goes inside another.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'nike' is an anagram of 'knie'.
'knie' enclosing 'f' is 'knife'.
'pen'+'knife'='PENKNIFE'
'in' acts as a link.
(Other definitions for penknife that I've seen before include "A Swiss army one has several blades and many tools" , "What may be used for carving" , "Handy little gadget" , "Pocket cutter" , "A Swiss army one is particularly handy" .)