Father leaves the pageant to be arranged by a deputy (5)
I believe the answer is:
agent
'a deputy' is the definition.
(thesaurus)
'father leaves the pageant to be arranged' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'leaves' suggests deleting specific letters.
'to be arranged' indicates anagramming the letters.
'pageant' with 'pa' removed is 'geant'.
'geant' is an anagram of 'AGENT'.
'by' is the link.
(Other definitions for agent that I've seen before include "One who acts for another" , "envoy" , "Spy - broker" , "Dealer" , "Person who does business on behalf of another" .)