This portrait is not Lady Charlotte Florentia Clive who was born in 1787. This Charlotte Clive lived between 1762 and 1795 and did not marry.
The coiffure is 1780s while the dress is the British casual style that had been worn for several decades. Lady Charlotte wears a criss-crossing bodice over her chemise.
Keywords: 1783, Romney, Charlotte Clive (1762-1795), Clive family, British, ling straight coiffure, ribbon headdress, chemise, modesty piece, scoop neckline, elbow length full virago sleeves, criss-cross bodice, vee neckline, strap sleeves, waist band, natural waistline, jeweled arm bands