Everyone filling favoured platform (6)
I believe the answer is:
pallet
'platform' is the definition.
(I know that pallet is a type of platform)
'everyone filling favoured' is the wordplay.
'everyone' becomes 'all' (all people).
'filling' is an insertion indicator.
'favoured' becomes 'pet' (as in a pet project).
'all' put inside 'pet' is 'PALLET'.
(Other definitions for pallet that I've seen before include "Wooden platform for moving and storing goods" , "Base used with fork-lift" , "Portable platform for storing or moving goods" , "Crude bed, lifting platform" , "heraldic strip" .)