Pump or boot (4)
I believe the answer is:
shoe
I believe this is a double definition.
'pump' is the first definition.
(I've seen this in another clue)
'boot' is the second definition.
(thesaurus)
(Other definitions for shoe that I've seen before include "mule, perhaps?" , "Footwear - playing-card dispenser - part of a brake" , "Work as a farrier" , "Oxford, perhaps" , "What's worn" .)