Direction taken in a Chelsea street (4)
I believe the answer is:
east
'direction' is the definition.
(compass direction)
'in a chelsea street' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EAST' is hidden in the letters of 'chelsea street'.
'taken' acts as a link.
(Other definitions for east that I've seen before include "On most maps it's right!" , "E" , "Tom's schoolfellow" , "Sunrise direction" , "An opponent of North" .)