Thin female, horribly slimy (6)
I believe the answer is:
flimsy
'thin' is the definition.
('flimsy' can be similar in meaning to 'thin')
'female horribly slimy' is the wordplay.
'female' becomes 'f' (abbreviation).
'horribly' indicates anagramming the letters.
'slimy' is an anagram of 'limsy'.
'f'+'limsy'='FLIMSY'
(Other definitions for flimsy that I've seen before include "Light and thin, easily torn or broken" , "Lacking strength and solidity" , "Weak, insubstantial" , "Light and thin, material or argument, perhaps" , "Lightweight" .)