Talk about second copper infiltrating Norfolk town (7)
I believe the answer is:
discuss
'talk about' is the definition.
(synonyms)
'second copper infiltrating norfolk town' is the wordplay.
'second' becomes 's' (common abbreviation).
'copper' becomes 'cu' (chemical symbol).
'infiltrating' is an insertion indicator.
'norfolk town' becomes 'diss' (I've seen this before).
's'+'cu'='scu'
'scu' going into 'diss' is 'DISCUSS'.
(Other definitions for discuss that I've seen before include "Verbally T [TREAT]" , "Take up" , "Go into" , "Consider" , "Debate" .)