Dull island, one crossed by granny with friend (9)
I believe the answer is:
inanimate
'dull' is the definition.
(I've seen this before)
'island one crossed by granny with friend' is the wordplay.
'island' becomes 'i' (geographical abbreviation).
'one crossed by granny' becomes 'nani' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' says to put letters next to each other.
'friend' becomes 'mate' (mate is a kind of friend).
'i'+'nani'+'mate'='INANIMATE'
Can you help me to learn more?
(Other definitions for inanimate that I've seen before include "Not endowed with life" , "spiritless" , "wooden" , "Not living" , "lacking in spirit" .)