Work advancing on the other side (8)
I believe the answer is:
opposing
'the other side' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
'work advancing' is the wordplay.
'work' becomes 'op' (short for opus).
'advancing' becomes 'posing' (I can't explain this - if you can you should believe this answer much more).
'op'+'posing'='OPPOSING'
'on' is the link.
Can you help me to learn more?
(Other definitions for opposing that I've seen before include "modelling after work" , "Going against" , "Contending" , "trying to end a sea of troubles by it?" , "Disapproving" .)