After work, Satie developed drugs (7)
I believe the answer is:
opiates
'drugs' is the definition.
(opiate is a kind of drug)
'after work satie developed' is the wordplay.
'after' means one lot of letters go next to another.
'work' becomes 'op' (abbreviation for opus**).
'developed' is an anagram indicator.
'satie' is an anagram of 'iates'.
'op' put next to 'iates' is 'OPIATES'.
(Other definitions for opiates that I've seen before include "Narcotic drugs" , "Poppy-derived drugs" , "Drugs that dull the feelings, sedatives" , "Branch of narcotics" , "Sedative drugs" .)