Feel sorry for redhead bird (6)
I believe the answer is:
regret
'feel sorry' is the definition.
(I've seen this before)
'redhead bird' is the wordplay.
'redhead' becomes 'r' (the head/first letter of 'red').
'bird' becomes 'egret' (egret is a kind of bird).
'r'+'egret'='REGRET'
'for' acts as a link.
(Other definitions for regret that I've seen before include "Wish undone" , "Feel sad or disappointed about" , "Contrition" , "Feeling or repentance or sorrow" , "Bad feeling" .)