Footwear used by firefighters? (5)
I believe the answer is:
'footwear' is the definition.
(pumps is a kind of footwear)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for pumps that I've seen before include "Forces liquid to move; light shoes" , "Water-raising devices" , "Moves fluid or gas by pressure or suction" , "Shoes; inflaters" , "Mechanical devices that move fluid or gas" .)