Climate unfortunately heats more round top of pole (10)
I believe the answer is:
atmosphere
'climate' is the definition.
(atmosphere is a kind of climate)
'unfortunately heats more round top of pole' is the wordplay.
'unfortunately' is an anagram indicator.
'round' is an insertion indicator.
'top of' suggests taking the first letters.
The first letter of 'pole' is 'p'.
'heats'+'more'='heatsmore'
'heatsmore' with letters rearranged gives 'atmoshere'.
'atmoshere' placed around 'p' is 'ATMOSPHERE'.
(Other definitions for atmosphere that I've seen before include "Surrounding ambience" , "Air" , "blue?" , "climate" , "prevailing mood" .)