A waterless loch can be the result of drought (7)
I believe the answer is:
dryness
'drought' is the definition.
(thesaurus)
'a waterless loch' is the wordplay.
'a waterless' becomes 'dry' (I've seen this before).
'loch' becomes 'ness' (Loch Ness in Scotland).
'dry'+'ness'='DRYNESS'
'can be the result of' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for dryness that I've seen before include "Characteristic of some wines" , "Lack of moisture" , "Freedom from moisture" , "Matter-of-fact quality (of humour)" , "Aridity" .)