Complete source of water for cattle outside house (8)
I believe the answer is:
thorough
'complete source of water' is the definition.
'thorough' can be an answer for 'complete' (I've seen this before). I am not certain of the 'source of water' bit.
'cattle outside house' is the wordplay.
'cattle' becomes 'trough' (I can't explain this - if you can you should give a lot more credence to this answer).
'outside' indicates putting letters inside.
'house' becomes 'ho' (abbreviation for house).
'trough' enclosing 'ho' is 'THOROUGH'.
'for' is the link.
Can you help me to learn more?
(Other definitions for thorough that I've seen before include "Complete and careful" , "Echaustive, complete" , "Meticulous - exhaustive" , "Detailed" , "Sweeping" .)