Answer
(Fatwa: 1758/1354=H/1429)
Singing and playing musical instrument is haram, while haldi and mehndi is halal within Shariah limits. There are several other customs which have different rulings. You may refer to Bahishti Zewar, there is nice and substantiated description of the matter. ?Islami Shadi? is also another good book on the topic. These books are very much useful.
For this reason, it is not allowed to let the pyjama or pant below the ankle, since it does not attract the attention of people generally and second if it is so and causes embarrassment then you can wear socks.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband