Apt to change look when removing current hat (8)
I believe the answer is:
volatile
'apt to change' is the definition.
(I've seen this before)
'current hat' is the wordplay.
'current' becomes 'vola' (I can't explain this - if you can you should give a lot more credence to this answer).
'hat' becomes 'tile' (old-fashioned term for a hat).
'vola'+'tile'='VOLATILE'
'look when removing' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for volatile that I've seen before include "Unstable and liable to change" , "Subject to sudden change, temperamental" , "Fickle; tending to vaporise" , "Easily vaporised" , "Subject to sudden changes" .)