More than enough work to maintain hospital department (6)
I believe the answer is:
plenty
'more than enough' is the definition.
(I've seen this before)
'work to maintain hospital department' is the wordplay.
'work' becomes 'ply' (to ply a trade is to work at it).
'to maintain' is an insertion indicator (maintain can mean to keep or preserve).
'hospital department' becomes 'ENT' (Ear, Nose and Throat department).
'ply' going around 'ent' is 'PLENTY'.
(Other definitions for plenty that I've seen before include "Masses" , "More than enough" , "Copiousness" , "A great deal" , "As much as necessary" .)