The work I took in was sleep-inducing (6)
I believe the answer is:
opiate
'sleep-inducing' is the definition.
(I've seen this in another clue)
'the work i took in' is the wordplay.
'the work' becomes 'op' (operation, work done in an operating theatre).
'took in' becomes 'ate' (take in can mean to eat).
'op'+'i'+'ate'='OPIATE'
'was' is the link.
(Other definitions for opiate that I've seen before include "painkiller" , "Sedating drug" , "A poet I become on this drug" , "Drug such as morphine" , "Does it ease pain" .)