Forehead and top of nose burnt by the sun (5)
I believe the answer is:
brown
'burnt by the sun' is the definition.
(brown can mean suntanned or sunburnt)
'forehead and top of nose' is the wordplay.
'forehead' becomes 'brow' (synonyms).
'and' means one lot of letters go next to another.
'top of' suggests taking the first letters.
The first letter of 'nose' is 'n'.
'brow'+'n'='BROWN'
(Other definitions for brown that I've seen before include "Dan --, The Da Vinci Code author" , "Colour (of the PM?)" , "Colour (at No 11?)" , "5,27 [PRIME MINISTER]" , "Mixture of red, yellow and blue" .)