Obscene flaw in such valued stock? (4,4)
I believe the answer is:
blue chip
'valued stock?' is the definition.
(type of trading stock)
'obscene flaw in' is the wordplay.
'obscene' becomes 'blue'.
'flaw in' becomes 'chip' (I've seen this before. I am not sure about the 'in' bit.**).
'blue'+'chip'='BLUE CHIP'
'such' is the link.
Can you help me to learn more?
(Other definitions for blue chip that I've seen before include "certain investment" , "Of high value" , "Excellent" , "Of shares, fairly reliable as investment if not gilt-edged" , "Highly prestigious" .)