Ultimately pot white, perhaps, being in tangle (5)
I believe the answer is:
twine
'tangle' is the definition.
(I know that tangle is a more specific form of the action twine)
'ultimately pot white perhaps' is the wordplay.
'ultimately' says to take the final letters.
'white perhaps' becomes 'wine' (white is a type of wine).
The final letter of 'pot' is 't'.
't'+'wine'='TWINE'
'being in' acts as a link.
(Other definitions for twine that I've seen before include "Garden string" , "String of twisted fibres" , "Curl; string" , "can get into knots" , "String, cord" .)