Puzzling trick covered by journalist in solemn observance (9)
I believe the answer is:
recondite
'puzzling' is the definition.
(recondite means puzzling or esoteric)
'trick covered by journalist in solemn observance' is the wordplay.
'trick' becomes 'con' (a con is a fraud or trick).
'covered by' means one lot of letters goes inside another.
'journalist' becomes 'ed' (short for editor).
'in' means one lot of letters goes inside another.
'solemn observance' becomes 'rite' (eg a religious rite).
'con' inserted into 'ed' is 'econd'.
'econd' placed within 'rite' is 'RECONDITE'.
(Other definitions for recondite that I've seen before include "Abstruse" , "Enigmatic" , "not widely known" , "Direct one to be obscure or difficult" , "Mysterious" .)