Puff pastry’s first up (6)
I believe the answer is:
praise
'puff' is the definition.
(I know that puff is a more specific form of the action praise)
'pastry's first up' is the wordplay.
'pastry's first' becomes 'p' (1st letter of 'pastry').
'up' becomes 'raise' (I've seen this in another clue).
'p'+'raise'='PRAISE'
(Other definitions for praise that I've seen before include "Speak well of" , "Express warm approval of (someone/something)" , "Eulogise" , "Express approval and admiration" , "flatter" .)