Nick taken inside cannot change (5)
I believe the answer is:
notch
'nick' is the definition.
(both can mean a small cut or impression)
'inside cannot change' is the wordplay.
'inside' says the answer is hidden in the clue.
'NOTCH' can be found hidden inside 'cannot change'.
'taken' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for notch that I've seen before include "Indentation, nick" , "Nick - incision" , "Cleft" , "Small V-shaped cut or indentation" , "Tallying incision" .)