Agree to certain download before cruise (7)
I believe the answer is:
approve
'agree to' is the definition.
(thesaurus)
'download before cruise' is the wordplay.
'download' becomes 'app' (phone or computer application).
'before' means one lot of letters go next to another.
'cruise' becomes 'rove' (both can mean to travel slowly).
'app'+'rove'='APPROVE'
'certain' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for approve that I've seen before include "Pass" , "Sanction, authorise" , "Officially accept as satisfactory" , "Commend, endorse" , "permit" .)