Unit dismissing one old part of hospital is inconvenient (8)
I believe the answer is:
untoward
'inconvenient' is the definition.
(I've seen this before)
'unit dismissing one old part of hospital' is the wordplay.
'dismissing' is a deletion indicator.
'one' becomes 'i' (Roman numeral).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'part of hospital' becomes 'ward' (hospitals have wards).
'unit' with 'i' removed is 'unt'.
'unt'+'o'+'ward'='UNTOWARD'
'is' is the link.
(Other definitions for untoward that I've seen before include "Unfortunate or unfavourable" , "Unexpected, inappropriate" , "Inopportune" , "Inappropriate, undesirable" , "Unseemly" .)