Do the deed with Don (a temporary associate) (9)
I believe the answer is:
bedfellow
'a temporary associate' is the definition.
'bedfellow' can be an answer for 'associate' (bedfellow is a kind of associate). I'm not certain of the 'a temporary' bit.
'do the deed with don' is the wordplay.
'do the deed with' becomes 'bed' (I am not sure about this - if you are sure you should believe this answer much more).
'don' becomes 'fellow' (I've seen this before).
'bed'+'fellow'='BEDFELLOW'
Can you help me to learn more?
(Other definitions for bedfellow that I've seen before include "Colleague" , "Person slept with" , "Mate" , "Close associate or partner" , "Partner (in the boudoir?)" .)