A lot of canvas needs wrapping, perfect for post to carry (8)
I believe the answer is:
mainsail
'a lot of canvas' is the definition.
I can't tell whether this defines the answer.
'wrapping perfect for post to carry' is the wordplay.
'wrapping' becomes 'ns' (I can't explain this - if you can you should give a lot more credence to this answer).
'perfect' becomes 'ai' (resembles An, informal term meaning excellent).
'for' means one lot of letters go next to another.
'post' becomes 'mail' (synonyms).
'to carry' is an insertion indicator.
'ns'+'ai'='nsai'
'nsai' going into 'mail' is 'MAINSAIL'.
'needs' acts as a link.
Can you help me to learn more?
(Other definitions for mainsail that I've seen before include "key equipment on board" , "Ship's largest canvas" , "Lowest canvas on the principle mast" , "Principal ship's canvas" , "Principal canvas sheet on ship" .)