Temperature one has to act quickly to reduce? (5,5)

'reduce?' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'temperature one has to act quickly' is the wordplay.
'temperature' becomes 'fever' (I have seen 'High temperature ' mean 'fever' so perhaps 'temperature' could also mean 'fever').
'one has' is a charade indicator (letters next to each other).
'to act quickly' becomes 'stage' (I can't explain this - if you can you should give a lot more credence to this answer).
'fever' put after 'stage' is 'STAGE FEVER'.

'to' is the link.

Can you help me to learn more?