Hurried up, pinching police officer’s bottom (5)
I believe the answer is:
nadir
'bottom' is the definition.
(I've seen this before)
'hurried up pinching police officer's' is the wordplay.
'hurried' becomes 'ran' (running is a kind of hurrying).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'pinching' means one lot of letters goes inside another (taking inside).
'police officer' becomes 'DI' (detective inspector).
'ran' reversed gives 'nar'.
'nar' enclosing 'di' is 'NADIR'.
(Other definitions for nadir that I've seen before include "Low point" , "Drain into the lowest point (5)" , "It's the depths" , "most unsuccessful point" , "lowest of the low" .)