Woman in tree is angler (6)
I believe the answer is:
fisher
'is angler' is the definition.
(I've seen this before)
'woman in tree' is the wordplay.
'woman' becomes 'she'.
'in' means one lot of letters goes inside another.
'tree' becomes 'fir' (fir is a kind of tree).
'she' inserted into 'fir' is 'FISHER'.
(Other definitions for fisher that I've seen before include "UK shipping forecast area" , "Marten; angler" , "Jeremy - (Beatrix Potter)" , "One who angles" .)