Colonists left, protected by dogs (8)
I believe the answer is:
settlers
'colonists' is the definition.
(I know this)
'left protected by dogs' is the wordplay.
I cannot quite understand how this works, but
'left' could be 'l' (common abbreviation) and 'l' is present in the answer.
'dogs' could be 'setters' (setter is a kind of dog) and 'setters' is located in the remaining letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for settlers that I've seen before include "who pay their bills?" , "Colonists" , "Trestles for pioneers" , "Pioneers, homesteaders" , "Immigrants" .)