Bitter end of uncoated tablet (4)
I believe the answer is:
ipad
'tablet' is the definition.
(tablet made by Apple)
'bitter end of uncoated' is the wordplay.
'bitter' becomes 'ipa' (I've seen this before).
'end of' says to take the final letters.
The final letter of 'uncoated' is 'd'.
'ipa'+'d'='IPAD'
(Other definitions for ipad that I've seen before include "Tablet computer from Apple" , "Small personal computer" .)