Bird starts to tend eggs right now (4)
I believe the answer is:
tern
'bird' is the definition.
(tern is a kind of bird)
'starts to tend eggs right now' is the wordplay.
'starts to' suggests taking the first letters.
The first letters of 'tend eggs right now' is 'TERN'.
(Other definitions for tern that I've seen before include "Fork-tailed relative of the gull" , "Gull-like seabird" , "Rent out this gull" , "Seabird related to the gull" , "Long-winged aquatic bird" .)