Wave to fellow railway worker (9)
I believe the answer is:
signalman
'railway worker' is the definition.
(I know that signalman is a type of railway worker)
'wave to fellow' is the wordplay.
'wave to' becomes 'signal' (I can't explain this - if you can you should believe this answer much more).
'fellow' becomes 'man' (fellow can mean a man).
'signal'+'man'='SIGNALMAN'
Can you help me to learn more?
(Other definitions for signalman that I've seen before include "Railway worker" , "Rail worker" , "one controlling traffic movement" , "Main slang (anag.)" , "Railway employee controlling points" .)