Unclued, I think 'site' is fine - it's part of the definition (along with the next two words.) The middle of the answer is given by the word before 'site'. I'm being circumspect to avoid spoiling this for anyone else!
The shading thing was ... an irritation, but not much more than that for me!
thanks, Peter. There's a four-letter word for 'cabbage', and inside that goes the three-letter word for 'on' (a particular sporting reference, used often).
You're almost there - I(sle) follows FUG for 'stale air', you just need the final letter from the surrounding anagram of 'are' (they are havens for certain kinds of flora - Latin).