Pole getting spiteful or hare-brained (6)
I believe the answer is:
scatty
'hare-brained' is the definition.
(I've seen this before)
'pole getting spiteful' is the wordplay.
'pole' becomes 's' (abbreviation for South, as in South Pole).
'getting' says to put letters next to each other.
'spiteful' becomes 'catty' (catty can mean spiteful or nasty).
's'+'catty'='SCATTY'
'or' acts as a link.
(Other definitions for scatty that I've seen before include "Informally crazy or feather-headed" , "dizzy" , "Slightly crazy" , "Informally crazy or muddle-headed - like jazz singer?" , "Bird-witted" .)