Old bit of ceremony the Spanish do very well (5)
I believe the answer is:
excel
'do very well' is the definition.
(I've seen this before)
'old bit of ceremony the spanish' is the wordplay.
'old' becomes 'ex'.
'bit of' suggests taking the first letters.
'the spanish' becomes 'el'.
The initial letter of 'ceremony' is 'c'.
'ex'+'c'+'el'='EXCEL'
(Other definitions for excel that I've seen before include "Perform extremely well" , "Do superbly well" , "Predominate in" , "Do brilliantly" , "Be very good at, better than others" .)