Classify first of grapes embraced by excited oenophile (10)
I believe the answer is:
pigeonhole
'classify' is the definition.
(I know that pigeonhole is a type of classify)
'first of grapes embraced by excited oenophile' is the wordplay.
'first of grapes' becomes 'g' (1st letter of 'grapes').
'embraced by' means one lot of letters goes inside another.
'excited' indicates anagramming the letters.
'oenophile' with letters rearranged gives 'pieonhole'.
'g' inserted within 'pieonhole' is 'PIGEONHOLE'.
(Other definitions for pigeonhole that I've seen before include "Recess in loft" , "wherein one may put post" , "Categorise" , "Classify; bird's home" .)