Give a speech for zero payment (5)
I believe the answer is:
orate
'give a speech' is the definition.
(oratory is public speaking)
'zero payment' is the wordplay.
'zero' becomes 'O' (O resembles 0).
'payment' becomes 'rate' (I can't explain this - if you can you should give a lot more credence to this answer).
'o'+'rate'='ORATE'
'for' is the link.
Can you help me to learn more?
(Other definitions for orate that I've seen before include "Make a pompous speech" , "Speak in public" , "Speak publicly" , "Pontificate" , "Talk pompously" .)