Workers accepting hard taskmaster's initial request (6)
I believe the answer is:
behest
'request' is the definition.
(I've seen this in another clue)
'workers accepting hard taskmaster's initial' is the wordplay.
'workers' becomes 'bees' (worker bees).
'accepting' indicates putting letters inside (inserted letters are accepted).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'initial' suggests taking the first letters.
The first letter of 'taskmasters' is 't'.
'bees' placed around 'h' is 'behes'.
'behes'+'t'='BEHEST'
(Other definitions for behest that I've seen before include "Command, bidding" , "Command - Thebes (anag)" , "Order" , "(At someone's) command" .)