River close to port and dock perhaps (5)
I believe the answer is:
tweed
'river' is the definition.
(river in Scotland)
'close to port and dock perhaps' is the wordplay.
'close to' suggests the final letters (the close of something is the end).
'and' is a charade indicator (letters next to each other).
'dock perhaps' becomes 'weed' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The final letter of 'port' is 't'.
't'+'weed'='TWEED'
Can you help me to learn more?
(Other definitions for tweed that I've seen before include "Rough woollen cloth" , "River on border between England and Scotland" , "Twilled cloth" , "Flow" , "See 7" .)