Authorise application to ramble (7)
I believe the answer is:
approve
'authorise' is the definition.
(approving is a kind of authorising)
'application to ramble' is the wordplay.
'application' becomes 'app'.
'to ramble' becomes 'rove' ('rove' can be a synonym of 'ramble').
'app'+'rove'='APPROVE'
(Other definitions for approve that I've seen before include "Pronounce (something) satisfactory" , "Pass" , "Say yes to" , "Commend, endorse" , "Give the green light" .)