Waves to agent briefly engaged by travelling guests (8)
I believe the answer is:
gestures
'waves' is the definition.
(I've seen this before)
'agent briefly engaged by travelling guests' is the wordplay.
'agent' becomes 'rep' (short for representative).
'briefly' means to remove the last letter.
'engaged by' means one lot of letters goes inside another (I've seen this in other clues).
'travelling' is an anagram indicator.
'rep' with its last letter taken away is 're'.
'guests' is an anagram of 'gestus'.
're' put inside 'gestus' is 'GESTURES'.
'to' is the link.
(Other definitions for gestures that I've seen before include "Expressive motions" , "Movements to express something" , "Make signs with hand movements" , "Motions that express thoughts" , "waves" .)