Current cost varied outside but he doesn't complain (5)
I believe the answer is:
stoic
'he doesn't complain' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'current cost varied outside' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'varied' indicates an anagram.
'outside' is an insertion indicator (some letters go outside others).
'cost' with letters rearranged gives 'stoc'.
'i' put into 'stoc' is 'STOIC'.
'but' acts as a link.
Can you help me to learn more?
(Other definitions for stoic that I've seen before include "Unemotional" , "Zeno, say" , "One able to endure hardship; philosopher" , "One who endures hardship uncomplainingly" , "Able to endure pain" .)