Poor reactions part creating delay (13)
I believe the answer is:
procrastinate
'delay' is the definition.
(procrastinating is a kind of delaying)
'poor reactions part' is the wordplay.
'poor' indicates anagramming the letters.
'reactions'+'part'='reactionspart'
'reactionspart' is an anagram of 'PROCRASTINATE'.
'creating' acts as a link.
(Other definitions for procrastinate that I've seen before include "Stall" , "Defer action" , "Be dilatory" , "Dilly-dally" , "Postpone" .)