🚀 go-pugleaf

I would like to write a macro that reserves registers and assigns them 
names using pararmeters passed to the macro. For example, a call such
as \doit{zork} would be expanded so that the result was \newinsert\bigzork.
I've made the following attempt:

    \def\doit#1{\expandafter\newinsert\csname big#1\endcsname}

and I receive the error that \newinsert is a forbidden command sequence in
a macro definition.  Does anyone have advice?

Note that this proceedure works wonderfully if I change it to generate macro 
definitions on macros that have different names.  The problem arises
when any \new"register" sequence is to be defined.

My goal is to be able to allocate multiple insert lists and operate on them
from a common macro.

Thanks,
Dick