20 down
Horse
and
cocaine
runs
through
old
addict
(7)
Horse and cocaine runs through old addict (7)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The definition is Horse — a courser being a swift one. For the wordplay, take cocaine (C) and runs (R) and run them through old (O) plus addict (USER), giving you C, then O, then USER with R inserted... which stacks up as C-O-U-R-S-E-R.