Old dealer finally cut deck (5)
I believe the answer is:
orlop
'deck' is the definition.
(orlop is a kind of deck)
'old dealer finally cut' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'finally' suggests the final letters.
'cut' becomes 'lop' (lopping is a kind of cutting**).
The final letter of 'dealer' is 'r'.
'o'+'r'+'lop'='ORLOP'
(Other definitions for orlop that I've seen before include "hold covering" , "deck at the lowest point" , "Lowest deck of a wooden sailing ship" , "Ship's lowest deck" , "part of ship" .)