Sorry to disagree, but I have never, ever, seen the letter 'g' clued as 'France'.
'art' can only really mean 'es' if there's some indication that the language being used is French. And if 'France' were also clueing the letter 'g', then it would be doing double-duty, which isn't allowed.
So here, the 'g' is the base (i.e. the first letter of) 'gilding'.