Holy type in choir reformed one refusing to face reality (7)
I believe the answer is:
ostrich
'one refusing to face reality' is the definition.
(someone putting their head in the sand)
'holy type in choir reformed' is the wordplay.
'holy type' becomes 'st' (abbreviation for saint).
'in' means one lot of letters goes inside another.
'reformed' indicates an anagram.
'choir' is an anagram of 'orich'.
'st' placed inside 'orich' is 'OSTRICH'.
(Other definitions for ostrich that I've seen before include "Nut-burying type" , "non-flyer?" , "Denier" , "Creature" , "Large flightless bird with fancy plumes" .)