Cases not kept in a set-top unit, unusually (11)
I believe the answer is:
outpatients
'cases' is the definition.
(outpatient is a kind of case)
'a set-top unit unusually' is the wordplay.
'unusually' is an anagram indicator.
'a'+'set'+'top'+'unit'='asettopunit'
'asettopunit' with letters rearranged gives 'OUTPATIENTS'.
'not kept in' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for outpatients that I've seen before include "They visit hospitals for treatment but don't stay" , "Put into seat (anag) - hospital department" .)