Hot pants and new, good underwear (5)
I believe the answer is:
thong
'underwear' is the definition.
(I know that thong is a type of underwear)
'hot pants and new good' is the wordplay.
'pants' indicates anagramming the letters (UK informal term for 'nonsense' or 'rubbish').
'and' means one lot of letters go next to another.
'new' becomes 'n' (abbreviation as in New Testament NT).
'good' becomes 'g' (abbreviation).
'hot' is an anagram of 'tho'.
'tho'+'n'+'g'='THONG'
(Other definitions for thong that I've seen before include "Narrow strip of leather - beach garment" , "Thin leather strip" , "flip-flop" , "Skimpy underwear" , "What offers little coverage" .)