Upset spectator with rain delay (13)
I believe the answer is:
procrastinate
'delay' is the definition.
(procrastinating is a kind of delaying)
'upset spectator with rain' is the wordplay.
'upset' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'spectator' after 'rain' is 'rainspectator'.
'rainspectator' is an anagram of 'PROCRASTINATE'.
(Other definitions for procrastinate that I've seen before include "Dally" , "Be dilatory" , "Delay taking action" , "Put off what should be done now" , "Dilly-dally" .)