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)
'clear through the canvas cover' is the wordplay.
'clear' becomes 'rid' (synonyms).
'through' is an insertion indicator (inserted letters go through the word).
'the canvas cover' becomes 'tent' (canvas shelter).
'rid' inserted within 'tent' is 'TRIDENT'.
'went' acts as a link.
This may not be correct. It may belong to another bit of the clue.
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" .)