A job so variable leads to abandonment of principles (8)
I believe the answer is:
apostasy
'abandonment of principles' is the definition.
'apostasy' can be an answer for 'abandonment' (apostasy is a kind of abandonment). I am not sure about the 'of principles' bit.
'a job so variable' is the wordplay.
'job' becomes 'post' (post is a kind of job).
'so' becomes 'as' (eg 'not as tall as me' means 'not so tall as me').
'variable' becomes 'y' (algebra).
'a'+'post'+'as'+'y'='APOSTASY'
'leads to' acts as a link.
Can you help me to learn more?
(Other definitions for apostasy that I've seen before include "defection" , "Abandonment of one's beliefs" , "Renunciation of a religious or political belief" , "abandoning principles" , "Desertion" .)