Is to think about wrongful employment (6)
I believe the answer is:
misuse
'wrongful employment' is the definition.
(I've seen this before)
'is to think about' is the wordplay.
'to think' becomes 'muse' (to muse on something is to think about it).
'about' means one lot of letters goes inside another.
'is' going inside 'muse' is 'MISUSE'.
(Other definitions for misuse that I've seen before include "Ill-treat" , "Ill-treatment" , "Maltreat" , "exploitation" , "Mistreat, misapply" .)