In recession corporations producing coarse material (4)
I believe the answer is:
smut
'coarse material' is the definition.
(smut can man coarse or obscene material)
'in recession corporations' is the wordplay.
'in recession' says the letters should be written in reverse (letters recede or go back).
'corporations' becomes 'tums' (corporation can humorously mean stomach fat).
'tums' back-to-front is 'SMUT'.
'producing' is the link.
(Other definitions for smut that I've seen before include "Soot, dirt, grit" , "Small bit of soot" , "Indecent talk - black mark" , "Pornographic material" , "Soot flake; fungal disease" .)