Join police around end of June (4)
I believe the answer is:
meet
'join' is the definition.
(meeting is a kind of joining)
'police around end of june' is the wordplay.
'police' becomes 'met' (I've seen this in other clues).
'around' is an insertion indicator.
'end of' indicates one should take the final letters.
The final letter of 'june' is 'e'.
'met' placed around 'e' is 'MEET'.
(Other definitions for meet that I've seen before include "Right and fitting" , "Come together or run into" , "Fitting - encounter" , "counter" , "Countryside assembly now perhaps not legal" .)