One twice disturbs Len in this relaxing morning (3-2)
I believe the answer is:
lie-in
'this relaxing morning' is the definition.
(a lie-in is extra time in bed)
'one twice disturbs len in' is the wordplay.
'one twice' can mean two substitutions for 'one'.
'one' becomes 'i' (roman numeral).
'one' becomes 'i' (roman numeral).
'disturbs' is an insertion indicator (inserted letters interrupt or disturb the word).
'in' indicates putting letters inside.
'i' going into 'len' is 'lien'.
'i' inserted inside 'lien' is 'LIE-IN'.
(Other definitions for lie-in that I've seen before include "Extended sleep" , "That extra hour or so in bed?" , "Period in bed longer than usual" , "Extra zeds in the morning" , "Extended overnight rest" .)