Detective in touch with politician's solicitor (4)
I believe the answer is:
pimp
'solicitor' is the definition.
(person who solicits clients for prostitutes)
'detective in touch with politician's' is the wordplay.
'detective' becomes 'pi' (private eye).
'in touch with' says to put letters next to each other.
'politician' becomes 'mp' (Member of Parliament).
'pi'+'mp'='PIMP'
(Other definitions for pimp that I've seen before include "who solicits business?" , "Arrange sex partners for others" .)