is that possible to order by a field that is related to a custom module in list view ?

I believe the 

'sortable' => false,

or

'sortable' => true,

setting for the field in question in the 

custom/modules/<your module>/clients/base/views/list/list.php 

will control that.

I have done a test but it does break  mysql query as the columns is not found. Francesca Shiekh do you think is there of the way to do that?

Sorry Rodrigo, my mistake, I replied too quickly without thinking of the field type.

I forgot that I reported a bug a long time ago about this.
There is an Enhancement request to allow sorting on relate fields:

portal.sugarondemand.com/

Sorry Rodrigo, my mistake, I replied too quickly without thinking of the field type.

I forgot that I reported a bug a long time ago about this.
There is an Enhancement request to allow sorting on relate fields:

portal.sugarondemand.com/