Sells millions on hot streak … (7)
I believe the answer is:
markets
'sells' is the definition.
(I've seen this in another clue)
'millions on hot streak' is the wordplay.
'millions' becomes 'm' (abbreviation).
'on' indicates putting letters inside.
'hot' is an anagram indicator (letters heated up or stimulated into a new order).
'streak' is an anagram of 'arkets'.
'm' going inside 'arkets' is 'MARKETS'.
(Other definitions for markets that I've seen before include "Trading places" , "Commercial activities where goods and services are bought and sold" , "Places for buying and selling" .)