A job as secretary ultimately 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'm not sure about the 'of principles' bit.
'a job as secretary ultimately' is the wordplay.
'job' becomes 'post' (post is a kind of job).
'ultimately' suggests the final letters.
The last letter of 'secretary' is 'y'.
'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 "Abandonment of one's beliefs" , "Renunciation of religious or political beliefs" , "defection" , "Renunciation of one's beliefs or principles" , "abandoning principles" .)