Inappropriate work contained in primer needing editing (8)
I believe the answer is:
improper
'inappropriate' is the definition.
(associated in meaning)
'work contained in primer needing editing' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'contained in' indicates putting letters inside.
'needing editing' is an anagram indicator.
'primer' anagrammed gives 'imprer'.
'op' going within 'imprer' is 'IMPROPER'.
(Other definitions for improper that I've seen before include "unfit" , "So it may appear a fraction" , "vulgar" , "Inappropriate" , "'Not suitable, right or appropriate (8)'" .)