Whinge about engineer cites drills (9)
I believe the answer is:
practices
'drills' is the definition.
(I know this)
'whinge about engineer cites' is the wordplay.
'whinge' becomes 'carp' (as in carping on about something).
'about' says the letters should be written in reverse.
'engineer' is an anagram indicator.
'carp' reversed gives 'prac'.
'cites' anagrammed gives 'tices'.
'prac'+'tices'='PRACTICES'
(Other definitions for practices that I've seen before include "Customary ways of operation" , "training exercises?" , "Businesses of a doctor or lawyer" , "Uses" , "Activities, procedures or customs" .)