Sleep regularly abandoned after bird's call (5)
I believe the answer is:
title
'call' is the definition.
(title can mean to call by a name)
'sleep regularly abandoned after bird's' is the wordplay.
'regularly abandoned' means one should take alternating letters (letters removed at regular intervals).
'after' means one lot of letters go next to another.
'bird' becomes 'tit' (tit is a kind of bird).
The alternate letters of 'sleep' are 'le'.
'le' put after 'tit' is 'TITLE'.
(Other definitions for title that I've seen before include "Right - name - rank" , "Name or designation" , "Proprietorship" , "Name of film, book etc" , "What could be professor's" .)