Tin, about to be returned, containing yellow kipper we hear (6)
I believe the answer is:
snorer
'kipper we hear' is the definition.
(a sleeper that can be heard)
'tin about to be returned containing yellow' is the wordplay.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'about' becomes 're' (common abbreviation for 'with reference to').
'to be returned' shows that the letters should be reversed in order (I've seen 'is returned' mean this).
'containing' indicates putting letters inside.
'yellow' becomes 'or' (heraldic term).
're' in reverse letter order is 'er'.
'sn'+'er'='sner'
'sner' placed around 'or' is 'SNORER'.
(Other definitions for snorer that I've seen before include "Maker of raucous nocturnal sounds" , "Noisy sleeper" , "Someone who makes snorting noises while asleep" .)