s'agisser in "she now wanted the theme of the party to be clowns"

Question

Instead of using être in 'to be clowns', can you use instead "s'agisser" (in the subjunctive present)?

Cécile Janty-Davies · Accepted Answer

Bonjour Sydney,,
If I have understood your question correctly, you are suggesting a verb that doesn't exist in French.
You may be thinking of the verb 's'agir de', and the expression 'il s'agit de ', which ( like 'il faut' ) only has one form, the impersonal il, and cannot be conjugated across any other forms but only across different tenses. So in the subjunctive, it would be 
il s'agisse de 
as used in the following examples -
Qu'il s'agisse de travail ou de loisirs, il donne toujours le meilleur de lui-même = Whether it involves work or leisure, he always gives his best.
Qu'il s'agisse d'une erreur ou d'une faute intentionnelle, les conséquences sont les mêmes = Whether it's a mistake or an intentional fault, the consequences are the same.
The impersonal expression 'Il sagit de' is hard to translate into English.
It can be -
to be about
to concern
to involve
to be a matter of
the thing is
But it cannot be used in the context you suggest, just plain old 'to be' in the subjunctive.
Hope this helps!