Duck making a comeback in meagre diet (5)
I believe the answer is:
eider
'duck' is the definition.
(eider is a type of duck)
'a comeback in meagre diet' is the wordplay.
'a comeback' shows that the letters should be reversed in order.
'in' indicates the answer is hidden within the clue.
'redie' can be found hidden inside 'meagre diet'.
'redie' in reverse letter order is 'EIDER'.
'making' acts as a link.
(Other definitions for eider that I've seen before include "Down-producing duck" , "Duck providing fine down" , "Northern sea duck" , "Species of duck" , "Variety of duck" .)