Notable female, a computer operator mostly (6)
I believe the answer is:
famous
'notable' is the definition.
('famous' can be a synonym of 'notable')
'female a computer operator mostly' is the wordplay.
'female' becomes 'f' (abbreviation).
'computer operator' becomes 'mouse' (I've seen this before).
'mostly' means to remove the last letter.
'mouse' with its final letter removed is 'mous'.
'f'+'a'+'mous'='FAMOUS'
(Other definitions for famous that I've seen before include "Well-known" , "Known-of widely" , "Eminent" , "Widely-known" , "Well known" .)