Do this and engineer penury and a touch of depression (8)
I believe the answer is:
underpay
'do this' is the definition.
The definition suggests a singular noun but the answer is not.
'engineer penury and a touch of depression' is the wordplay.
'engineer' is an anagram indicator.
'and' is a charade indicator (letters next to each other).
'touch of' suggests taking the first letters.
The first letter of 'depression' is 'd'.
'penury'+'a'+'d'='penuryad'
'penuryad' with letters rearranged gives 'UNDERPAY'.
'and' is the link.
(Other definitions for underpay that I've seen before include "Use staff meanly" , "Give too little remuneration" , "Give too little money" .)