Go and tread unwarily around the pierhead (6)
I believe the answer is:
depart
'go' is the definition.
(I know that go can be written as depart)
'tread unwarily around the pierhead' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'pierhead' could be 'p' (head letter of 'pier') and 'p' is found in the answer.
The remaining letters 'dear' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for depart that I've seen before include "Prated (anag.)" , "Retire from" , "Make an exit" , "Leave (6)" , "Quit" .)