Man-eater catching writer in channel (8)
I believe the answer is:
cannibal
'man-eater' is the definition.
(I know that man-eater can be written as cannibal)
'writer in channel' is the wordplay.
'writer' becomes 'nib' (something which writes).
'in' is an insertion indicator.
'channel' becomes 'canal' (synonyms).
'nib' placed inside 'canal' is 'CANNIBAL'.
'catching' is the link.
(Other definitions for cannibal that I've seen before include "One eating own species" , "Eater of one's own kind" , "One eats human flesh" , "Person who has someone for dinner?" , "Person eating human flesh" .)