It's not indirectly affected like the piston chamber (8)
I believe the answer is:
cylinder
'the piston chamber' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cylinder that I've seen before include "Chamber in which piston moves in engine" , "Roller-shaped object" , "Swiss-roll shape" , "Long, round figure" , "Type of round container, for gas say" .)