Decrepit little bird found on step (4,2)
I believe the answer is:
past it
'decrepit little' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'bird found on step' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'found on' says to put letters next to each other.
'step' becomes 'pas' (I've seen this before).
'tit' after 'pas' is 'PAST IT'.
Can you help me to learn more?
(Other definitions for past it that I've seen before include "Getting over the hill" , "no longer fresh" , "Beyond the age of effectiveness, too old" , "No longer in one's prime" , "Spit at, being too old or decrepit" .)