Idles around going into decline (5)
I believe the answer is:
slide
'decline' is the definition.
(I've seen this in another clue)
'idles around' is the wordplay.
'around' indicates an anagram.
'idles' is an anagram of 'SLIDE'.
'going into' acts as a link.
(Other definitions for slide that I've seen before include "Picture" , "Transparency" , "Playground chute" , "leading to a fall" , "Make mild fun of" .)