Woman takes it to be important (5)
I believe the answer is:
vital
'important' is the definition.
(I know that important can be written as vital)
'woman takes it' is the wordplay.
'woman' becomes 'val' (val is a name for a woman).
'takes' means one lot of letters goes inside another.
'val' placed around 'it' is 'VITAL'.
'to be' acts as a link.
(Other definitions for vital that I've seen before include "Crucially important, essential" , "Essential, life-giving" , "Essential; lively" , "Critical; life-sustaining" , "Characteristic of life" .)