Charlie departs from Kentish Town in disguise (5)
I believe the answer is:
cover
'disguise' is the definition.
(cover can mean a disguise or secret identity)
'charlie departs from kentish town' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'from' indicates named letters should be taken away.
'kentish town' becomes 'Dover' (town in Kent).
'dover' with 'd' removed is 'over'.
'c'+'over'='COVER'
'in' is the link.
(Other definitions for cover that I've seen before include "Overlay" , "the point of cricket" , "Extend over (an area)" , "Lid, travel (distance)" , "Shroud" .)