Daughter put in first green herbaceous plant (8)
I believe the answer is:
bedstraw
'herbaceous plant' is the definition.
(bedstraw is a kind of herbaceous plant)
'daughter put in first green' is the wordplay.
'daughter put' becomes 'd' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'first' becomes 'best' (similar in meaning).
'green' becomes 'raw' (synonyms).
'd' put inside 'best' is 'bedst'.
'bedst'+'raw'='BEDSTRAW'
Can you help me to learn more?
(Other definitions for bedstraw that I've seen before include "Best ward (anag) - plant" , "Plant once used for stuffing mattresses" , "makes a poor lie" , "Plant once used to stuff mattresses" , "Plant formerly used in mattresses" .)