River's hard work — go away (5)
I believe the answer is:
indus
'river's' is the definition.
(Indian river)
'hard work go away' is the wordplay.
'hard work' becomes 'industry' (being industrious).
'go' becomes 'try' (both can mean an attempt).
'away' is a deletion indicator.
'industry' with 'try' taken away is 'INDUS'.
(Other definitions for indus that I've seen before include "Major Asian river" , "Pakistani river" , "River rising in Tibet" , "River of India and Pakistan" , "Sacred flower" .)