Reach old woman in boat returning (5)
I believe the answer is:
gamut
'reach' is the definition.
(I know that gamut is a type of reach)
'old woman in boat returning' is the wordplay.
'old woman' becomes 'ma' (both can mean someone's mother).
'in' indicates putting letters inside.
'boat' becomes 'tug' (tug is a kind of boat).
'returning' says the letters should be written in reverse.
'ma' put into 'tug' is 'tumag'.
'tumag' reversed gives 'GAMUT'.
(Other definitions for gamut that I've seen before include "Full extent" , "Entire range" , "Compass, scale" , "Ambit" , "The whole range of, say emotions" .)