Do the inside edges in red (7)
I believe the answer is:
crimson
'red' is the definition.
(I know that red can be written as crimson)
'do the inside edges in' is the wordplay.
'do' becomes 'con' (both can mean to defraud).
'the inside edges' becomes 'rims' (rim is a kind of edge. I am not sure about the 'inside' bit.).
'in' is an insertion indicator.
'con' enclosing 'rims' is 'CRIMSON'.
Can you help me to learn more?
(Other definitions for crimson that I've seen before include "Microns of colour" , "Blood-red" , "Flush" , "Become red-faced" , "Looking embarrassed" .)