SHAFAQNA- Dear Brother, Salamun `alaykum wa Rahmatullahi wa Barakatuhu. With apologies for the delay, the answer is as follows: Bismihi Ta`ala
Your eminence has stated that it is not permissible to wear the clothing of the aggressors, or propagate their cultural attack against the Muslims. You have also clarified the issue in stating that for Muslims born and who live in the West, it is permissible to wear Western clothing as long as it also doesn’t actively promote cultural aggression against the Muslims. (These questions have been asked relating some other fatwas about western clothes, see: 29 Questions)
Question 1: If Muslims from several different nationalities meet for a religious gathering, what is the most appropriate way for them to dress: according to the oref of each person’s country and people, or according to the oref of the Muslims of their host country? If it is not a religious gathering, does that change how they dress when they meet each other?
Answer 1) He has the choice of doing either one, rather he may wear any kind of clothes [with the condition that he preserves the mentioned condition] and does not cause mafsadah like wearing women clothes or clothes which attract attention.
Question 2: What is the best way for our Iranian women to observe hejab in the West? Some wear manteau and rusari, and some only rusari (with loose-fitting clothes). Is it obligatory for them to at least wear manteau and rusari or even chador to establish their Iranian-Islamic identity, or is any clothing which meets the criteria of modest dress sufficient?
Answer 2) Any dress covers her body and does not show its beauties, although it is preferred to wear the chador.
Question 3: Some American converts to Islam dress in a manner which they consider to be in the sunnat of hazrat Mohammad and the Imams of his household (AS): turban (ammameh), or, prayer hat (shab-kolah), cloak (aba), and baggy pants (shalvar kordi). This draws a lot of attention to them from both Muslims and non-Muslims, and sometimes prevents them from finding gainful employment. What is the ruling on this type of dress? How should we advice them?
Answer 3) Wearing shalvar is not from the sunnah. Yet, wearing (ammamah)is mustahab, but if it causes some mafsadah (like you mentioned) then there is no harm if not wearing it.
Wallahul`Alim. With prayers for your success, wassalam.