Cold - Geordie's content to go out with top on (5)
I believe the answer is:
gelid
'cold' is the definition.
(similar in meaning)
'geordie's content to go out with top on' is the wordplay.
I cannot quite see how this works, but
'top' could be 'lid' (lid is a kind of top) and 'lid' is located in the answer.
The remaining letters 'ge' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gelid that I've seen before include "Icy cold - glide (anag)" , "Glacial" , "Extremely cold, frozen" .)