Grounds to force son to accept terms on a regular basis (8)
I believe the answer is:
premises
'grounds' is the definition.
(thesaurus)
'force son to accept terms on a regular basis' is the wordplay.
'force' becomes 'prise' (I've seen this before**).
'son' becomes 's'.
'to accept' means one lot of letters goes inside another.
'on a regular basis' means one should take alternating letters.
The alternating letters of 'terms' are 'em'.
'prise'+'s'='prises'
'prises' enclosing 'em' is 'PREMISES'.
'to' is the link.
(Other definitions for premises that I've seen before include "Places of business" , "Property" , "Assumptions" , "A business's site and buildings" , "States" .)