Record Welsh ceremony (5)
I believe the answer is:
write
'record' is the definition.
(I've seen this in another clue)
'welsh ceremony' is the wordplay.
'welsh' becomes 'W' (abbreviation).
'ceremony' becomes 'rite' (rite is a kind of ceremony).
'w'+'rite'='WRITE'
(Other definitions for write that I've seen before include "Create (manuscript)" , "Use a pen/pencil" , "Put pen to paper" , "Put down in black and white" , "Compose; correspond" .)