Tailor is fool to hurry back of blazer (8)
I believe the answer is:
clothier
'tailor' is the definition.
(I've seen this before)
'fool to hurry back of blazer' is the wordplay.
'fool' becomes 'clot' (I've seen this before).
'to hurry' becomes 'hie' ('hie' can be a synonym of 'hurry').
'back of blazer' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'clot'+'hie'+'r'='CLOTHIER'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for clothier that I've seen before include "Supplier of things to wear" , "Outfitter" , "One selling material or garments" , "trader" , "Shopkeeper" .)