Nick climbs around it after I set up (9)
I believe the answer is:
initiated
'set up' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?
'nick climbs around it after i' is the wordplay.
'nick' becomes 'detain' (I can't justify this - if you can you should give a lot more credence to this answer).
'climbs' is a reversal indicator.
'around' indicates putting letters inside.
'after' is a charade indicator (letters next to each other).
'detain' in reverse letter order is 'niated'.
'niated' placed around 'it' is 'nitiated'.
'nitiated' after 'i' is 'INITIATED'.
Can you help me to learn more?
(Other definitions for initiated that I've seen before include "Accepted into a group by way of a ritual" , "Started" , "Those admitted into the mysteries" , "Began" , "Begun" .)