West Pier’s new cleaner (5)
I believe the answer is:
wiper
'cleaner' is the definition.
(something which cleans)
'west pier's new' is the wordplay.
'west' becomes 'W' (synonyms).
'new' indicates anagramming the letters.
'pier' anagrammed gives 'iper'.
'w'+'iper'='WIPER'
(Other definitions for wiper that I've seen before include "Window-cleaner" , "car accessory" , "Windscreen cleaner" , "contact in the electrical world" , "someone drying off?" .)