Philip goes east on tube (4)
I believe the answer is:
pipe
'tube' is the definition.
(pipes are tubular)
'philip goes east' is the wordplay.
I cannot quite see how this works, but
'philip' could be 'pip' (can be a nickname for Philip) and 'pip' is found within the answer.
'east' could be 'e' (synonyms) and 'e' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'on' is the link.
Can you help me to learn more?
(Other definitions for pipe that I've seen before include "Tube carrying liquid or gas" , "Smoker's item" , "Fluid or gas transporter" , "Tube to carry water, gas etc" , "11th" .)