Spite revealed in awful stain in loch (9)
I believe the answer is:
nastiness
'spite' is the definition.
(I know that spite can be written as nastiness)
'awful stain in loch' is the wordplay.
'awful' indicates an anagram.
'in' indicates putting letters inside.
'loch' becomes 'ness' (Loch Ness in Scotland).
'stain' is an anagram of 'astin'.
'astin' going within 'ness' is 'NASTINESS'.
'revealed in' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for nastiness that I've seen before include "Malevolence" , "Pollution" , "ill humour" , "repugnance" , "hostility" .)