We're told charge is zero for bird from fire (7)
I believe the answer is:
phoenix
'bird from fire' is the definition.
'phoenix' can be an answer for 'bird' (I've seen this before). I'm not sure about the 'from fire' bit.
'we're told charge is zero' is the wordplay.
I cannot quite see how this works, but
'zero' could be 'nix' (synonyms) and 'nix' is found in the answer.
This explanation may well be incorrect...
'for' acts as a link.
Can you help me to learn more?
(Other definitions for phoenix that I've seen before include "Legendary bird - tragic actor - Arizona capital" , "capital in America" , "Legendary bird -- Arizona city" , "Legendary Arabian bird" , "part of Arizona" .)