Iberia? Portugal and Spain almost all in sun, possibly (9)
I believe the answer is:
peninsula
'iberia?' is the definition.
(iberia is a kind of peninsula)
'portugal and spain almost all in sun possibly' is the wordplay.
'portugal' becomes 'p' (common abbreviation eg on car number plates).
'and' means one lot of letters go next to another.
'spain' becomes 'e' (abbreviation for Espana).
'almost' means to remove the last letter (almost the whole word is kept).
'possibly' indicates an anagram.
'all' with its last letter removed is 'al'.
'al'+'in'+'sun'='alinsun'
'alinsun' with letters rearranged gives 'ninsula'.
'p'+'e'+'ninsula'='PENINSULA'
(Other definitions for peninsula that I've seen before include "Scandinavia, perhaps" , "Malay for one" , "Alpine sun (anag.)" , "Land mostly surrounded by water" , "the Balkans and Italy, for example" .)