Vacation? That is going back with son’s holding attraction (7)
I believe the answer is:
leisure
'vacation?' is the definition.
(vacation is a kind of leisure)
'going back with son's holding attraction' is the wordplay.
'going back with' becomes 'ei' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'holding' is an insertion indicator.
'attraction' becomes 'lure' (lure is a kind of attraction).
'ei'+'s'='eis'
'eis' placed inside 'lure' is 'LEISURE'.
'that is' acts as a link.
Can you help me to learn more?
(Other definitions for leisure that I've seen before include "Non-work activity" , "idle hours" , "Time for relaxation and pleasure" , "Enjoyment of free time" , "casual wear" .)