Boyfriend joins family across capital, ultimately to see Olympic Torch? (8)
I believe the answer is:
flambeau
'olympic torch?' is the definition.
'boyfriend joins family across capital ultimately' is the wordplay.
'boyfriend' becomes 'beau' ('beau' can be a synonym of 'boyfriend'**).
'joins' means one lot of letters go next to another.
'family' becomes 'fam'.
'across' means one lot of letters goes inside another.
'ultimately' says to take the final letters.
The last letter of 'capital' is 'l'.
'fam' placed around 'l' is 'flam'.
'beau' put after 'flam' is 'FLAMBEAU'.
'to see' is the link.
(Other definitions for flambeau that I've seen before include "Torch; candlestick" , "One may be burning" , "Burning torch" , "Flaming torch" , "Old blazer" .)