A couple taking part in networking (3)
I believe the answer is:
two
'a couple' is the definition.
(a couple can mean two of something)
'part in networking' is the wordplay.
'part in' indicates a hidden word.
'TWO' is hidden in the letters of 'networking'.
'taking' acts as a link.
(Other definitions for two that I've seen before include "prime -- that's not odd" , "Pair; hour after lunch" , "Old song 'Tea for . . .'" , "One plus one" , "Between one and three" .)