The spear went clear through the canvas cover (7)
I believe the answer is:
trident
'the spear' is the definition.
(trident is a kind of spear)
'went clear through the canvas cover' is the wordplay.
I cannot quite understand how this works, but
'clear' could be 'rid' (synonyms) and 'rid' is located in the answer.
'canvas' could be 'tent' (I've seen this in other clues) and 'tent' is found in the leftover 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 trident that I've seen before include "Neptune's spear - missile" , "Red tint (anag.)" , "spear carried at sea" , "Nuclear missile" , "3-pronged spear" .)