Rogue personal problem down below (7)
I believe the answer is:
bounder
'rogue' is the definition.
(thesaurus)
'personal problem down below' is the wordplay.
'personal problem' becomes 'bo' (informal abbreviation for body odour).
'down below' becomes 'under' (synonyms).
'bo'+'under'='BOUNDER'
(Other definitions for bounder that I've seen before include "Untrustworthy type (once)" , "A cad - or a kind of jumper" , "A hop-along cad?" , "despicable man" , "The skipper" .)