Writer's block, and poet is upset (7)
I believe the answer is:
notepad
'writer's block' is the definition.
(block of paper)
'and poet is upset' is the wordplay.
'is upset' indicates an anagram (I've seen 'are upset' mean this).
'and'+'poet'='andpoet'
'andpoet' anagrammed gives 'NOTEPAD'.
(Other definitions for notepad that I've seen before include "Tablet" , "Pocket-sized computer" , "Place for recording" , "Block of writing paper; computer" , "writer's block" .)