Inexperienced legislators giving description of some climate impacts? (10)

I believe the answer is:
greenhouse
'description of some climate impacts?' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'inexperienced legislators' is the wordplay.
'inexperienced' becomes 'green' (similar in meaning).
'legislators' becomes 'house' (I can't justify this - if you can you should believe this answer much more).
'green'+'house'='GREENHOUSE'
'giving' acts as a link.
Can you help me to learn more?
(Other definitions for greenhouse that I've seen before include "A place for growing" , "somewhere hot" , "Glass building for rearing plants" , "associated with harmful gases" , "Horticulturalists' glass building" .)
