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.
From 18thcenturyblog.com/2012/03/george-romney.
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