Police force heading west, and east, take great risks (4)
I believe the answer is:
dice
'take great risks' is the definition.
(to dice is to gamble or take risks)
'police force heading west and east' is the wordplay.
'police force' becomes 'cid' (abbreviation for Criminal Investigation Department).
'heading west' shows that the letters should be reversed in order.
'and' says to put letters next to each other.
'east' becomes 'e' (synonyms).
'cid' reversed gives 'dic'.
'dic'+'e'='DICE'
(Other definitions for dice that I've seen before include "Gamble; cut into cubes" , "Cut into small cubes" , "Make into chips" , "Gambling pieces" , "Small cube" .)