Lackey occasionally returns bearing cake (6)
I believe the answer is:
eclair
'cake' is the definition.
(eclair is a type of cake)
'lackey occasionally returns bearing' is the wordplay.
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'returns' says the letters should be written in reverse.
'bearing' becomes 'air' (both can mean an attitude or pose).
The alternating letters of 'lackey' are 'lce'.
'lce' reversed gives 'ecl'.
'ecl'+'air'='ECLAIR'
(Other definitions for eclair that I've seen before include "Oblong cream puff" , "Comedienne" , "Dainty" , "Bakery item" , "Sweet thing" .)