Some work to stop chap finding port (6)
I believe the answer is:
bergen
'port' is the definition.
(I've seen this before)
'some work to stop chap' is the wordplay.
'some work' becomes 'erg' (scientific unit of work).
'to stop' means one lot of letters goes inside another (inserted letters plug or stop a gap).
'chap' becomes 'Ben' (man's name).
'erg' going into 'ben' is 'BERGEN'.
'finding' acts as a link.
(Other definitions for bergen that I've seen before include "SW Norway port" , "Second city of Norway" , "Norwegian port city" , "Port city of Norway" .)