Cow that circles about, having been oddly ignored (8)
I believe the answer is:
threaten
'cow' is the definition.
(I've seen this before)
'that circles about having been oddly ignored' is the wordplay.
'circles' indicates putting letters inside.
'about' becomes 're' ('re' means regarding or about).
'having' means one lot of letters go next to another.
'oddly ignored' means one should take alternating letters (letters in odd-numbered positions are removed).
The alternate letters of 'been' are 'en'.
'that' going around 're' is 'threat'.
'threat'+'en'='THREATEN'
(Other definitions for threaten that I've seen before include "Utter menaces" , "Impend, portend" , "Foreshadow" , "Utter intentions of injury or punishment" , "Be menacing" .)