Bird's plucky, heading off north (5)
I believe the answer is:
raven
'bird's' is the definition.
(raven is a kind of bird)
'plucky heading off north' is the wordplay.
'plucky' becomes 'brave' (I've seen this before).
'heading off' means to remove the first letter.
'north' becomes 'n' ('N' can be a synonym of 'north').
'brave' with its initial letter taken off is 'rave'.
'rave'+'n'='RAVEN'
(Other definitions for raven that I've seen before include "Glossy black colour" , "Bird with hoarse, croaking cry" , "Hungrily devour" , "Flighty type" , "Type of crow" .)