Holy man in no spirit for a quack remedy (7)
I believe the answer is:
nostrum
'a quack remedy' is the definition.
(I've seen this before)
'holy man in no spirit' is the wordplay.
'holy man' becomes 'st'.
'in' means one lot of letters goes inside another.
'spirit' becomes 'rum' (I've seen this before).
'no'+'rum'='norum'
'st' placed inside 'norum' is 'NOSTRUM'.
'for' acts as a link.
(Other definitions for nostrum that I've seen before include "Some think it helps" , "Must Ron take a quack remedy?" , "Quack cure" , "secret potion" , "Patent medicine of highly questionable value" .)