Weka machine learning software from which .arff attribute files actually originate supports natively export of CSV format. We do not know about any other program or software that would be capable of this arff to csv conversion.
Convert Weka attribute-relation data to Comma Separated Value.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert arff to csv on Windows
A machine learning software to solve data mining problems
Convert from arff file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.