Pay no regard to a trade concession (8)
I believe the answer is:
discount
'trade concession' is the definition.
'discount' can be an answer for 'concession' (thesaurus). I am not certain of the 'trade' bit.
'pay no regard' is the wordplay.
'pay no' becomes 'dis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'regard' becomes 'count' (I've seen this before).
'dis'+'count'='DISCOUNT'
'to a' acts as a link.
Can you help me to learn more?
(Other definitions for discount that I've seen before include "Reduce in price" , "Reduction in price for conduits" , "Tend not to believe" , "Disbelieve" , "Ignore - trade concession" .)