Late in the year, briefly attending hospital department — it's dirty (8)
I believe the answer is:
indecent
'dirty' is the definition.
(associated in meaning)
'late in the year briefly attending hospital department' is the wordplay.
'late in the year briefly' becomes 'in Dec' (in December).
'attending' means one lot of letters go next to another.
'hospital department' becomes 'ENT' (abbreviation for Ear, Nose and Throat department).
'indec'+'ent'='INDECENT'
'it's' acts as a link.
(Other definitions for indecent that I've seen before include "Immodest, gross" , "Lewd" , "Lacking propriety" , "Gross, unbecoming" , "Risque" .)