Keep going, intrinsically gripping always (9)
I believe the answer is:
persevere
'keep going' is the definition.
(thesaurus)
'intrinsically gripping always' is the wordplay.
'intrinsically' becomes 'perse' ('per se' can be a synonym of 'intrinsically').
'gripping' indicates putting letters inside.
'always' becomes 'ever' ('ever' can be a synonym of 'always').
'perse' going around 'ever' is 'PERSEVERE'.
(Other definitions for persevere that I've seen before include "Remain" , "Struggle on!" , "Be persistent, refuse to stop" , "Keep going" , "Continue despite difficulties" .)