He has to look around for a perfect ending (5)
I believe the answer is:
peter
'he has to look' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'around for a perfect ending' is the wordplay.
'around' is an insertion indicator.
'for a' becomes 'per' ('per' can mean 'for each' person or 'for a' person).
'perfect ending' becomes 'te' (I can't explain this - if you can you should give a lot more credence to this answer).
'per' placed around 'te' is 'PETER'.
Can you help me to learn more?
(Other definitions for peter that I've seen before include "Boy's name (maybe blue)" , "Sir - - Ustinov" , "One of the Apostles" , "Fellow < safe" , "foundation for church" .)