Noble's heading for birthday party (5)
I believe the answer is:
brave
'noble's' is the definition.
(thesaurus)
'heading for birthday party' is the wordplay.
'heading for' indicates taking the first letters.
'party' becomes 'rave' (I've seen this before).
The first letter of 'birthday' is 'b'.
'b'+'rave'='BRAVE'
(Other definitions for brave that I've seen before include "Indian warrior" , "Hardy" , "Displaying courage" , "Intrepid and fearless" , "Defy" .)