C-shell: variable syntax question

There is a possibility to set a variable, having an another variable in it's name:
prompt% setenv PRT one
prompt% setenv VAR_${PRT} value
prompt%

So, this way the VAR_one = "value" and could be viewed:
prompt% echo VAR_one
value
prompt%

Q: How to view a variable having another var in it's name?
The echo $VAR_${PRT} or echo ${VAR_${PRT}} does not work