It travels fast say the attendants (7,5)
I believe the answer is:
express train
'it travels fast' is the definition.
The definition suggests a singular noun which matches the answer.
'say the attendants' is the wordplay.
'say' becomes 'express' (to express something is to say it).
'the attendants' becomes 'train' (train can mean attendants following a royal).
'express'+'train'='EXPRESS TRAIN'
Can you help me to learn more?
(Other definitions for express train that I've seen before include "Speedy transport" , "Fast form of transport" , "fast online service?" , "occasionally halting transport" , "Rapid means of transport" .)