Follow behind, right in the rear (5)
I believe the answer is:
trail
'follow behind' is the definition.
'right in the rear' is the wordplay.
'right' becomes 'r' (common abbreviation).
'in' means one lot of letters goes inside another.
'the rear' becomes 'tail' (tail is a kind of rear).
'r' going into 'tail' is 'TRAIL'.
(Other definitions for trail that I've seen before include "Follow - track" , "Beaten path; track" , "Rough path" , "Path or track through wild or hilly country" , "Scent or track followed in hunting" .)