Companion in seat crumpled bag (6)
I believe the answer is:
sachet
'bag' is the definition.
(sachet is a kind of bag)
'companion in seat crumpled' is the wordplay.
'companion' becomes 'ch' (I've seen this in other clues).
'in' indicates putting letters inside.
'crumpled' is an anagram indicator.
'seat' with letters rearranged gives 'saet'.
'ch' put inside 'saet' is 'SACHET'.
(Other definitions for sachet that I've seen before include "Small soft bag, containing perfumed powder perhaps" , "Small sealed packet" , "Small bag or sealed plastic pack" , "Small bag - chaste (anag)" , "Chaste as a sealed plastic bag" .)