Give a detailed account of story in trailer that's abbreviated and modified (6)
I believe the answer is:
retail
'give a detailed account of story' is the definition.
(retail can mean to repeat a story in detail)
'trailer that's abbreviated and modified' is the wordplay.
'that's abbreviated' means to remove the last letter (the word is shortened or abbreviated).
'and modified' indicates anagramming the letters.
'trailer' with its last letter taken away is 'traile'.
'traile' anagrammed gives 'RETAIL'.
'in' acts as a link.
(Other definitions for retail that I've seen before include "The sale of goods to the public" , "This trade serves the general public" , "Sell in small quantities" , "Sale of goods to customers" , "This trade sells to the general public" .)