Frenzy of a fellow to get a first-class return (5)
I believe the answer is:
mania
'frenzy' is the definition.
(thesaurus)
'a fellow to get a first-class return' is the wordplay.
'a fellow' becomes 'man' (I've seen this before**).
'to get' is a charade indicator (letters next to each other).
'a first class' becomes 'ai' (Am - top quality).
'return' is a reversal indicator.
'ai' in reverse letter order is 'ia'.
'man'+'ia'='MANIA'
'of' acts as a link.
(Other definitions for mania that I've seen before include "serious obsession" , "wildness" , "Excessive enthusiasm" , "Obsessive enthusiasm" , "Insanity" .)