Approve Bill having time to pay (8)
I believe the answer is:
accredit
'approve' is the definition.
(thesaurus)
'bill having time to pay' is the wordplay.
'bill' becomes 'ac' (short for account).
'having' means one lot of letters go next to another.
'time to pay' becomes 'credit' (I've seen this before).
'ac'+'credit'='ACCREDIT'
(Other definitions for accredit that I've seen before include "Trace CID and send them with credentials" , "Authorize" , "Give official recognition to" , "Certify, ascribe" , "Endorse" .)