One who works hard to reveal remains of cairn? (8)
I believe the answer is:
dogsbody
'one who works hard to' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'remains of cairn?' is the wordplay.
I cannot really see how this works, but
'remains' could be 'body' (as in a corpse) and 'body' is found in the answer.
'of' could be 'o' and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'reveal' is the link.
Can you help me to learn more?
(Other definitions for dogsbody that I've seen before include "Go by odds to find menial worker" , "Person doing menial jobs" , "One who has to do all the boring jobs" , "Menial servant" , "Drudge" .)