Reflective talk in decline (3)
I believe the answer is:
sag
'decline' is the definition.
(I've seen this in other clues)
'reflective talk' is the wordplay.
'reflective' is a reversal indicator.
'talk' becomes 'gas' (gas can mean to chat).
'gas' backwards is 'SAG'.
'in' is the link.
(Other definitions for sag that I've seen before include "Subsidence" , "Sink under weight" , "Droop, sink in the middle" , "Sink, hang down" , "Droop in the middle - it's gas" .)