Dreadful waste of hard work (5)
I believe the answer is:
sweat
'hard work' is the definition.
(synonyms)
'dreadful waste' is the wordplay.
'dreadful' indicates anagramming the letters.
'waste' anagrammed gives 'SWEAT'.
'of' is the link.
(Other definitions for sweat that I've seen before include "(Of argument) intense" , "Soldier" , "Perspire" , "Waste (anag.)" , "Male perspiration?" .)