American guy joining that chap in uninspiring opera (2,6)
I believe the answer is:
la boheme
'opera' is the definition.
(I've seen this before)
'american guy joining that chap in uninspiring' is the wordplay.
'american guy' becomes 'Bo'.
'joining' means one lot of letters go next to another.
'that chap' becomes 'he'.
'in' is an insertion indicator.
'uninspiring' becomes 'lame'.
'bo'+'he'='bohe'
'bohe' inserted into 'lame' is 'LA BOHEME'.
(Other definitions for la boheme that I've seen before include "18 [OPERA]" , "Opera by Puccini" , "musical work" .)