Permit for two ports starting off in Washington going all the way back (5)
I believe the answer is:
allow
'permit' is the definition.
(I know that permit can be written as allow)
'two ports starting off in washington going all the way back' is the wordplay.
I cannot really see how this works, but
'ports' could be 'll' (abbreviation for left - 'port' on ships - repeated) and 'll' is found in the answer.
'way' could be 'w' (Compass direction - West) and 'w' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'for' acts as a link.
Can you help me to learn more?
(Other definitions for allow that I've seen before include "Sanction" , "Permit or agree" , "brook" , "Permit or concede" , "Admit as acceptable" .)