Manual workers getting depressed easily (5,4)
I believe the answer is:
hands down
'easily' is the definition.
(synonyms)
'manual workers getting depressed' is the wordplay.
'manual workers' becomes 'hands' (eg factory hands).
'getting' means one lot of letters go next to another.
'depressed' becomes 'down' (synonyms).
'hands'+'down'='HANDS-DOWN'
(Other definitions for hands down that I've seen before include "producing sentences?" , "without effort" , "with ease" , "without difficulty" , "Workers not functioning" .)