Trees burning somewhere in Hampshire (9)
I believe the answer is:
aldershot
'somewhere in hampshire' is the definition.
(I've seen this before)
'trees burning' is the wordplay.
'trees' becomes 'alders' (alder is a kind of tree).
'burning' becomes 'hot' (similar in meaning).
'alders'+'hot'='ALDERSHOT'
(Other definitions for aldershot that I've seen before include "town occupied by soldiers?" , "Hampshire town with military camp" , "Home of the British Army" , "Hampshire military base" , "In army camp" .)