Glamorous former lover with old nervous habit (6)
I believe the answer is:
exotic
'glamorous' is the definition.
(thesaurus)
'former lover with old nervous habit' is the wordplay.
'former lover' becomes 'ex'.
'with' means one lot of letters go next to another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'nervous habit' becomes 'tic' (I've seen this before).
'ex'+'o'+'tic'='EXOTIC'
(Other definitions for exotic that I've seen before include "Strikingly strange or unusual" , "Foreign; strikingly colourful" , "Romantically strange" , "Foreign; glamorous" , "Strange, rare or foreign" .)