Main boat-building part of Canada (8)
I believe the answer is:
manitoba
'part of canada' is the definition.
('Manitoba' is part of 'canada')
'main boat-building' is the wordplay.
'building' indicates an anagram.
'main'+'boat'='mainboat'
'mainboat' with letters rearranged gives 'MANITOBA'.
(Other definitions for manitoba that I've seen before include "part of N America" , "Canadian lake" , "Strange boatman I find in Canada" , "Canadian territory" , "region bordering Hudson Bay" .)