Sacred work is a tiny bit tacky at the outset (5)
I believe the answer is:
motet
'sacred work' is the definition.
(sacred piece of music)
'tiny bit tacky at the outset' is the wordplay.
'tiny bit' becomes 'mote' (I've seen this in another clue).
'at the outset' says to take the initial letters (the outset is the beginning).
The first letter of 'tacky' is 't'.
'mote'+'t'='MOTET'
'is a' is the link.
(Other definitions for motet that I've seen before include "work by Tallis, for example" , "Musical composition" , "10 [COMPOSITION]" , "Word; fixed period" , "Anthem or church cantata" .)