One spiteful woman about to go tight-lipped? (8)
I believe the answer is:
taciturn
'tight-lipped?' is the definition.
(taciturn means not saying much)
'one spiteful woman about to go' is the wordplay.
'one' becomes 'i' (Roman numeral).
'spiteful woman' becomes 'cat' (I've seen this in another clue).
'about' says the letters should be written backwards.
'to go' becomes 'turn' (as in one's go or turn in a game).
'i'+'cat'='icat'
'icat' back-to-front is 'taci'.
'taci'+'turn'='TACITURN'
(Other definitions for taciturn that I've seen before include "Tight-lipped" , "Disinclined towards conversation" , "Far from talkative" , "Aloof" , "Habitually uncommunicative, saying little" .)