Excellent and fast, suppressing male illness (7)
I believe the answer is:
ailment
'illness' is the definition.
(an ailment is an illness or health problem)
'excellent and fast suppressing male' is the wordplay.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'and' means one lot of letters go next to another.
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'suppressing' is an insertion indicator.
'male' becomes 'm' (common abbreviation).
'lent' placed around 'm' is 'lment'.
'ai'+'lment'='AILMENT'
(Other definitions for ailment that I've seen before include "Physical disorder" , "I lament (anag.)" , "Tummy upset, for instance" , "Sickness" , "Minor illness" .)