Heading for somewhere where it's extremely hot, wearing these? (6)
I believe the answer is:
shades
'wearing these?' is the definition.
The definition suggests an adverb but the answer is not.
'heading for somewhere where it's extremely hot' is the wordplay.
'heading for' says to take the initial letters.
'where it's extremely hot' becomes 'hades'.
The first letter of 'somewhere' is 's'.
's'+'hades'='SHADES'
(Other definitions for shades that I've seen before include "'Tints, tones (6)'" , "Cool sunglasses or archaic ghosts" , "Ghosts or slang sunglasses" , "Sunglasses (informal)" , "blinds?" .)