Set out to be a warm-hearted, bright fellow (5)
I believe the answer is:
array
'set out' is the definition.
(synonyms)
'to be a warm-hearted bright fellow' is the wordplay.
'to be a' becomes 'a'.
'warm' becomes 'thermal' (similar in meaning).
'hearted' says to take the centre.
'bright fellow' becomes 'ray' (man's name. I am not sure about the 'bright' bit.).
The middle letter of 'thermal' is 'r'.
'a'+'r'+'ray'='ARRAY'
Can you help me to learn more?
(Other definitions for array that I've seen before include "Marshal" , "Order - arrangement" , "Matrix; elaborate clothing" , "Imposing assembly" , "Line up" .)