The most common and most likely answer to this crossword clue is the 7 plus 6 letter word BARGAIN HUNTER
I've seen this crossword clue in The Guardian
B
A
R
G
A
I
N
H
U
N
T
E
R
More clues leading to the result BARGAIN HUNTER
Buddy explains!

The straight part
We know that "One after a good deal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one after a good deal = bargain hunter.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.