Showed opposition — but put on another performance? (7)
I believe the answer is:
reacted
'showed opposition' is the definition.
(react could mean to oppose something)
'put on another performance?' is the wordplay.
'put on' means one lot of letters go next to another (some letters go on or after others).
'another' becomes 're' (I've seen this in other clues).
'performance?' becomes 'acted' (I can't justify this - if you can you should believe this answer much more).
're' next to 'acted' is 'REACTED'.
'but' is the link.
(Other definitions for reacted that I've seen before include "Responded to a stimulus" , "Showed a response" .)