Canvas giving trouble after ship crosses river (8)
I believe the answer is:
staysail
'canvas' is the definition.
(staysail is a kind of canvas)
'trouble after ship crosses river' is the wordplay.
I cannot quite see how this works, but
'trouble' could be 'ail' (synonyms) and 'ail' is found within the answer.
'river' could be 'tay' (River Tay) and 'tay' is located in the answer.
'ship' could be 'ss' (prefix in ship names eg SS Great Britain) and 'ss' is present in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'giving' acts as a link.
(Other definitions for staysail that I've seen before include "part of the rigging" , "Something on ship" .)