Marketing event in Trafford town (4)

I believe the answer is:

sale

I'm a little stuck... Click here to teach me more about this clue!

'marketing' is the definition.
(I know that sale is a type of marketing)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for sale that I've seen before include "Exchange of goods for fixed amount" , "See 12 Down" , "Cut-price offer" , "Period of low prices" , "Auction; Cheshire town" .)

I've seen this clue in The Sun.

Want a hint initially instead of a full solution? Install my app