Long-suffering person, small, getting to one cold (5)
I believe the answer is:
stoic
'long-suffering' is the definition.
(stoic can mean brave when suffering)
'person small getting to one cold' is the wordplay.
'person small' becomes 'sto' (I can't justify this - if you can you should give a lot more credence to this answer).
'getting to' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'cold' becomes 'C' (eg on taps).
'sto'+'i'+'c'='STOIC'
Can you help me to learn more?
(Other definitions for stoic that I've seen before include "One who doesn't complain" , "not given to complaining" , "Someone seemingly indifferent to pleasure or pain" , "One indifferent to fortune, pleasure and pain" , "Person indifferent to pleasure or pain" .)