Park officer blowing top in rage (5)
I believe the answer is:
anger
'rage' is the definition.
(thesaurus)
'park officer blowing top' is the wordplay.
'park officer' becomes 'ranger' (I've seen this before).
'blowing top' means to remove the first letter.
'ranger' with its initial letter removed is 'ANGER'.
'in' acts as a link.
(Other definitions for anger that I've seen before include "Provoke annoyance" , "Annoyance, displeasure" , "Irk" , "Irateness" , "Feeling of vexation" .)