Damp cargo, short judge gathers (7)
I believe the answer is:
amasses
'gathers' is the definition.
('amass' can be a synonym of 'gather')
'damp cargo short judge' is the wordplay.
'damp cargo' becomes 'am' (I am not sure about this - if you are sure you should believe this answer much more).
'short' means to remove the last letter.
'judge' becomes 'assess' (to assess is to judge or rate).
'assess' with its last letter taken away is 'asses'.
'am'+'asses'='AMASSES'
Can you help me to learn more?
(Other definitions for amasses that I've seen before include "Collects" , "'Accumulates, gathers (7)'" , "Gathers together" .)