Parking regulator the police have hesitation in using? (5)
I believe the answer is:
meter
'parking regulator' is the definition.
(I've seen this in another clue)
'police have hesitation in using?' is the wordplay.
I cannot really see how this works, but
'police' could be 'met' (London Metropolitan Police) and 'met' is found in the answer.
'hesitation' could be 'er' (sound made while hesitating - um, er) and 'er' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'the' acts as a link.
Can you help me to learn more?
(Other definitions for meter that I've seen before include "Measuring device as for electricity usage (5)" , "Device for measuring and recording" , "Something measuring" , "Device for recording, say, usage (5)" , "Device that measures, say, electricity usage" .)