Dismal starters of jam and yellowing bird (4,3)
I believe the answer is:
blue jay
'bird' is the definition.
(blue jay is a kind of bird)
'dismal starters of jam and yellowing' is the wordplay.
'dismal' becomes 'blue' (I've seen this before).
'starters of' says to take the initial letters.
The first letters of 'jam and yellowing' is 'jay'.
'blue'+'jay'='BLUE JAY'
(Other definitions for blue jay that I've seen before include "North American bird" , "N. American bird" .)