Cadge soft drug, at first, for sleeping policeman (5,4)
I believe the answer is:
speed bump
'sleeping policeman' is the definition.
(I've seen this before)
'cadge soft drug at first' is the wordplay.
'cadge' becomes 'bum' (synonyms).
'soft' becomes 'p' (musical abbreviation for 'piano', soft).
'drug at' becomes 'speed' (I can't explain this - if you can you should believe this answer much more).
'first' says to put letters next to each other.
'bum'+'p'='bump'
'bump' after 'speed' is 'SPEED BUMP'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for speed bump that I've seen before include "Sleepng policeman" , "Sleeping policeman" , "traffic checker" , "Traffic-calming measure (B, not H)" , "Traffic-calming device" .)