Included in formulae developed setting up work in the drugs trade (4)
I believe the answer is:
deal
'work in the drugs trade' is the definition.
'deal' can be an answer for 'trade' (synonyms). I'm unsure of the 'work in the drugs' bit.
'included in formulae developed setting up' is the wordplay.
'included in' indicates a hidden word.
'setting up' shows that the letters should be reversed in order.
'laed' is hidden within 'formulae developed'.
'laed' back-to-front is 'DEAL'.
Can you help me to learn more?
(Other definitions for deal that I've seen before include "Trade; pine wood" , "A port, a bargain" , "Distribute playing cards" , "Distribute (cards); wood" , "Plank of softwood timber" .)