Sparseness of Sun - God, Rodney's gutted about it (6)
I believe the answer is:
rarity
'sparseness' is the definition.
(thesaurus)
'sun god rodney's gutted about it' is the wordplay.
'sun god' becomes 'ra' (Egyptian god).
'gutted' says to hollow out the word (remove centre letters) (to gut something is to remove its insides).
'about' means one lot of letters goes inside another.
'rodney' with its centre removed is 'ry'.
'ry' enclosing 'it' is 'rity'.
'ra'+'rity'='RARITY'
'of' is the link.
(Other definitions for rarity that I've seen before include "Uncommon item or event" , "Something very scarce, probably valuable" , "Unusual item" , "Something uncommon" , "Infrequent occurrence" .)