Everyone enthralled by favourite straw mattress (6)
I believe the answer is:
pallet
'straw mattress' is the definition.
(I've seen this before)
'everyone enthralled by favourite' is the wordplay.
'everyone' becomes 'all' (all people).
'enthralled by' indicates putting letters inside ('enthral' can mean 'capture').
'favourite' becomes 'pet' (synonyms).
'all' inserted into 'pet' is 'PALLET'.
(Other definitions for pallet that I've seen before include "Base used with fork-lift" , "Portable platform for storing or moving goods" , "For mixing paint or moving goods" , "Stacking platform; straw bed" , "Handling platform" .)