Rambling and leaving sons unprotected (5,2)
I believe the answer is:
going on
'rambling' is the definition.
'leaving sons unprotected' is the wordplay.
'leaving' becomes 'going' ('going' can be a synonym of 'leaving').
'unprotected' says to take the centre.
The central letters of 'sons' are 'on'.
'going'+'on'='GOING ON'
'and' acts as a link.
(Other definitions for going on that I've seen before include "reluctant to stop?" , "Almost" , "Continuing" .)