Garments that fade in the terrible sun (6)
I believe the answer is:
undies
'garments' is the definition.
Although both the answer and definition are nouns, they are not in the same form of the noun.
'fade in the terrible sun' is the wordplay.
'fade' becomes 'die' (fade can mean to die away).
'in' indicates putting letters inside.
'the terrible' indicates an anagram.
'sun' is an anagram of 'uns'.
'die' put into 'uns' is 'UNDIES'.
'that' acts as a link.
Can you help me to learn more?
(Other definitions for undies that I've seen before include "Used in (anag) -- unmentionables" , "Lingerie -- is nude (anag)" , "clothing not normally seen" , "Personal attire" , "Pants" .)