Old man’s step (3)
I believe the answer is:
pas
'old man's step' is the definition.
'pas' can be an answer for 'step' (I've seen this before). I'm unsure of the 'old man's' bit.
'old man's step' is the wordplay.
'old man' becomes 'pa' (both can mean father).
'step' becomes 's' (this could be a standard abbreviation which I don't know about).
'pa'+'s'='PAS'
Can you help me to learn more?
(Other definitions for pas that I've seen before include "Dance movement" , "Dance step" , "A bit of ballet" , "Office workers" , "Dad's" .)