Hospital department I depend on completely (8)
I believe the answer is:
entirely
'completely' is the definition.
(I know that completely can be written as entirely)
'hospital department i depend on' is the wordplay.
'hospital department' becomes 'ENT' (abbreviation for Ear, Nose and Throat department).
'depend' becomes 'rely' (I've seen this before).
'on' means one lot of letters go next to another.
'ent'+'i'+'rely'='ENTIRELY'
(Other definitions for entirely that I've seen before include "Completely and absolutely" , "Wholly, totally" , "Altogether" , "Wholly, completly" , "Fully or absolutely" .)