It's exhausting for tenor from one wedding band (6)
I believe the answer is:
tiring
'it's exhausting' is the definition.
('tire' can be a synonym of 'exhaust')
'tenor from one wedding band' is the wordplay.
'tenor' becomes 't'.
'from' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral**).
'wedding band' becomes 'ring' (I've seen this before).
't'+'i'+'ring'='TIRING'
'for' acts as a link.
(Other definitions for tiring that I've seen before include "Laborious" , "Growing weary or bored" , "Causing weariness" , "Becoming sleepy" , "Exhausting or tedious" .)