Bloke returning excellent thing (5)
I believe the answer is:
mania
'thing' is the definition.
(I've seen this before)
'bloke returning excellent' is the wordplay.
'bloke' becomes 'man' (I've seen this before).
'returning' is a reversal indicator.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'ai' reversed gives 'ia'.
'man'+'ia'='MANIA'
(Other definitions for mania that I've seen before include "Violent madness or extreme enthusiasm" , "Craze; overexcitement" , "Excessive enthusiasm" , "Aberration" , "Mental disorder that results in excessive or violent responses" .)