Profile of Tory leading expedition (7)
I believe the answer is:
contour
'profile' is the definition.
(thesaurus)
'tory leading expedition' is the wordplay.
'tory' becomes 'con' (abbreviation for Conservative).
'leading' means one lot of letters go next to another (some letters go in front of others).
'expedition' becomes 'tour'.
'con'+'tour'='CONTOUR'
'of' acts as a link.
(Other definitions for contour that I've seen before include "Defining line" , "Line on map indicating height" , "Outline (of land)" , "Outline, profile" , "Silhouette" .)