Linen chest that's new. Look inside (7)
I believe the answer is:
clothes
'linen' is the definition.
(thesaurus)
'chest that's new look inside' is the wordplay.
'that's new' indicates anagramming the letters.
'look' becomes 'lo' (archaic exclamation meaning 'look!').
'inside' is an insertion indicator.
'chest' with letters rearranged gives 'cthes'.
'cthes' placed around 'lo' is 'CLOTHES'.
(Other definitions for clothes that I've seen before include "Togs" , "Garments" , "Worn items" , "Attire" , "Items of apparel" .)