Good floating platform required hard work (5)
I believe the answer is:
graft
'hard work' is the definition.
(graft can mean working hard)
'good floating platform required' is the wordplay.
'good' becomes 'g' (abbreviation).
'floating platform' becomes 'raft' (I've seen this in another clue).
'required' says to put letters next to each other.
'g'+'raft'='GRAFT'
(Other definitions for graft that I've seen before include "Transfer of tissue - hard work!" , "Slip" , "Labour" , "Hard work - illicit gain" , "Hard work - swindle" .)