Waiter seeing a race finish with worker (9)
I believe the answer is:
attendant
'waiter' is the definition.
(I've seen this before)
'a race finish with worker' is the wordplay.
'race' becomes 'tt'.
'finish' becomes 'end' (synonyms).
'with' is a charade indicator (letters next to each other).
'worker' becomes 'ant' (worker is a type of ant).
'a'+'tt'+'end'+'ant'='ATTENDANT'
'seeing' is the link.
(Other definitions for attendant that I've seen before include "escort" , "guard" , "Related" , "Accompanying - custodian" , "Helper, aide" .)