Twin having fallen from campanile? (4,6)
I believe the answer is:
dead ringer
'twin' is the definition.
(I've seen this in another clue)
'fallen from campanile?' is the wordplay.
I cannot quite see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is located in the answer.
This explanation may well be incorrect...
'having' acts as a link.
(Other definitions for dead ringer that I've seen before include "Quasimodo at end of novel?" , "one looks very much like another" , "double" , "Likeness" , "Someone who looks identical to another (slang)" .)