Stranger started on first dead redback (5)
I believe the answer is:
odder
'stranger' is the definition.
(more odd)
'started on first dead redback' is the wordplay.
'started' means to remove the last letter (I've seen 'start of' mean this).
'first dead' becomes 'd' (dst letter of 'dead').
'redback' becomes 'der' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' with its last letter taken away is 'o'.
'o'+'d'+'der'='ODDER'
(Other definitions for odder that I've seen before include "more rum" , "More unusual" , "More peculiar" , "Stranger" , "More strange or less even" .)