Imagine arresting French nobleman in bed! (6)
I believe the answer is:
seduce
'bed' is the definition.
(bed can mean to seduce or sleep with)
'imagine arresting french nobleman' is the wordplay.
'imagine' becomes 'see' (seeing is a kind of imagining).
'arresting' indicates putting letters inside.
'french nobleman' becomes 'duc' ('duke' in French).
'see' placed around 'duc' is 'SEDUCE'.
'in' is the link.
(Other definitions for seduce that I've seen before include "Beguile" , "Lead astray, tempt" , "Lure or entice into bad behaviour" , "Debauch" , "Charm - deprave" .)