Trainee not quite joining reduced staff in crime busting force (8)
I believe the answer is:
interpol
'force' is the definition.
(I've seen this before)
'trainee not quite joining reduced staff in' is the wordplay.
'trainee' becomes 'intern' (intern can mean a trainee worker).
'not quite' means to remove the last letter.
'joining' means one lot of letters go next to another.
'reduced staff in' becomes 'pol' (I can't explain this - if you can you should believe this answer much more).
'intern' with its last letter taken off is 'inter'.
'inter'+'pol'='INTERPOL'
'crime busting' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for interpol that I've seen before include "world force" , "Multinational crime fighters" , "International co-ordinating police body" , "International law enforcement agency" , "Forces cooperating" .)