Admit NHS is appallingly inconsistent (3-3-4)
I believe the answer is:
hit-and-miss
'inconsistent' is the definition.
(I've seen this before)
'admit nhs is appallingly' is the wordplay.
'appallingly' is an anagram indicator (I've seen this in other clues).
'admit'+'nhs'+'is'='admitnhsis'
'admitnhsis' is an anagram of 'HIT-AND-MISS'.
(Other definitions for hit-and-miss that I've seen before include "Haphazard" , "Inconsistent" .)