Port worker who makes a deduction? (6)
I believe the answer is:
docker
'port worker' is the definition.
(I've seen this before)
'who makes a deduction?' is the wordplay.
'who' becomes 'doc'.
'makes a deduction?' becomes 'ker' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'doc'+'ker'='DOCKER'
Can you help me to learn more?
(Other definitions for docker that I've seen before include "Ship loader/unloader" , "colleagues at the wharf?" , "Cargo handler" , "He loads and unloads ships" , "One unloading" .)