Zero in maths worried Hardy, for one (6)
I believe the answer is:
thomas
'hardy for one' is the definition.
The definition suggests a singular noun which matches the answer.
'zero in maths worried' is the wordplay.
'zero' becomes 'O' (O resembles 0).
'in' means one lot of letters goes inside another.
'worried' is an anagram indicator.
'maths' is an anagram of 'thmas'.
'o' placed inside 'thmas' is 'THOMAS'.
Can you help me to learn more?
(Other definitions for thomas that I've seen before include "-- Moore, Irish poet" , "See 18" , "Doubting apostle" , "One of the Twelve Apostles" , "He had doubts" .)