Preparing fish, empty sac during handling (9)

'preparing fish' is the definition.
(removing scales from fish)

'empty sac during handling' is the wordplay.
'empty' says to hollow out the word (remove centre letters).
'during' is an insertion indicator.
'handling' becomes 'dealing' (dealing is a kind of handling).
'sac' with its centre taken out is 'sc'.
'sc' inserted into 'dealing' is 'DESCALING'.