Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
A spouse can look at the other naked thus seeing one's spouse in sexy dress is legal with a greater reason since there is no Hijab or cover between them. Allah Says (interpretation of meaning): {They are Lîbas [i.e. body cover, or screen, or Sakan, (i.e. you enjoy the pleasure of living with her)], for you and you are the same for them.}[2:187]. It is also permissible for a wife to dance before her husband provided this is free from music and musical instruments, except the al-Daff (tambourine).
Therefore, if a husband asks his wife to wear sexy clothes and dance, she is encouraged to do so, and she will even get reward for pleasing her husband, Insha Allah.
A wife is rewarded highly for the obedience to her husband; besides that it strengthens the marital ties and increases love and affection.
Allah knows best.