Trim old man getting about (4)
I believe the answer is:
pare
'trim' is the definition.
('pare' can be a synonym of 'trim')
'old man getting about' is the wordplay.
'old man' becomes 'pa' (both can mean father).
'getting' is a charade indicator (letters next to each other).
'about' becomes 're' (regarding**).
'pa'+'re'='PARE'
(Other definitions for pare that I've seen before include "Shave or peel" , "Whittle" , "Cut down gradually" , "Remove the skin from" , "Decrease gradually" .)