Disciple grabbing senior, one bound to keep going (7,2)
I believe the answer is:
soldier on
'keep going' is the definition.
(I've seen this before)
'disciple grabbing senior one bound' is the wordplay.
'disciple' becomes 'son' (son can figuratively mean a follower or disciple).
'grabbing' indicates putting letters inside.
'senior' becomes 'older' (senior can mean the older of two people).
'one' becomes 'i' (Roman numeral).
'bound' means one lot of letters goes inside another.
'son' placed around 'older' is 'solderon'.
'solderon' enclosing 'i' is 'SOLDIER ON'.
'to' acts as a link.
(Other definitions for soldier on that I've seen before include "keep going" , "Persist in spite of difficulties" , "Doggedly continue" , "plug away" , "Persevere (colloq.)" .)