begin{filecontents}{jobname.bib}
@misc {zzz,
author="Zzzz",
title={verb|"{a}| makes "{a}},
journal={{renewcommand"{boo} " a}},
publisher={
begin{tabbing}
  a = b
end{tabbing}
}
}
end{filecontents}
documentclass{article}
usepackage{biblatex}
addbibresource{jobname.bib}
begin{document}

begin{tabbing}
  a = b
end{tabbing}

cite{zzz}
printbibliography

end{document}

list{publisher}{1}{%
    {begin{tabbing} a b̄ end{tabbing}}%
  field{journaltitle}{{renewcommand"{boo} ä}}
  field{title}{verb|ä| makes ä}