Secretary brought in clocked writer's block (7)
I believe the answer is:
notepad
'writer's block' is the definition.
(block of paper)
'secretary brought in clocked' is the wordplay.
'secretary' becomes 'PA' (abbreviation for personal assistant).
'brought in' is an insertion indicator.
'clocked' becomes 'noted' (I can't explain this - if you can you should believe this answer much more).
'pa' inserted within 'noted' is 'NOTEPAD'.
Can you help me to learn more?
(Other definitions for notepad that I've seen before include "Place for recording" , "PC" , "Block writer might have" , "A secretary may have one" , "Block of writing paper; computer" .)