Map required in talk about river (5)
I believe the answer is:
chart
'map' is the definition.
(I know that chart is a more specific form of the action map)
'in talk about river' is the wordplay.
'in' is an insertion indicator.
'talk about' becomes 'chat' (I've seen this before. I am not sure about the 'about' bit.).
'river' becomes 'r' (abbreviation for river).
'chat' placed around 'r' is 'CHART'.
'required' is the link.
Can you help me to learn more?
(Other definitions for chart that I've seen before include "Table or graph" , "Table or diagram" , "Visual display of information" , "Navigational map" , "Map to assist navigation by sea" .)