Priest initially up for worship (6)
I believe the answer is:
praise
'for worship' is the definition.
(praise can mean worship or adoration)
'priest initially up' is the wordplay.
'initially' says to take the initial letters.
'up' becomes 'raise' (I've seen this in another clue).
The initial letter of 'priest' is 'p'.
'p'+'raise'='PRAISE'
(Other definitions for praise that I've seen before include "Be aware of (something)" , "Commend or laud" , "Speak highly of" , "Extol, laud" , "flatter" .)