Man in Cambridge network (4)
I believe the answer is:
gene
'man' is the definition.
'in cambridge network' is the wordplay.
'in' indicates a hidden word.
'GENE' is hidden in the letters of 'cambridge network'.
(Other definitions for gene that I've seen before include "What makes us different" , "Hereditary unit on chromosome" , "Part of chromosome" , "Hereditary determinant" , "Basic unit of heredity" .)