Son about to polish axe (5)
I believe the answer is:
scrub
'axe' is the definition.
(I've seen this before)
'son about to polish' is the wordplay.
'son' becomes 's'.
'about' becomes 'c' (abbreviation for 'circa'**).
'to polish' becomes 'rub' (polish meaning rub to make shiny).
's'+'c'+'rub'='SCRUB'
(Other definitions for scrub that I've seen before include "Rub hard to clean" , "Undergrowth" , "Rub hard with a brush" , "Vegetation consisting of stunted trees or bushes" , "Cancel; clean vigorously" .)