Dig up seed scattered around end of plot that's detached (13)
I believe the answer is:
disinterested
'detached' is the definition.
(thesaurus)
'dig up seed scattered around end of plot' is the wordplay.
'dig up' becomes 'disinter' (disinterring is a kind of digging up**).
'scattered' indicates anagramming the letters.
'around' is an insertion indicator.
'end of' indicates one should take the final letters.
The final letter of 'plot' is 't'.
'seed' with letters rearranged gives 'esed'.
'esed' placed around 't' is 'ested'.
'disinter'+'ested'='DISINTERESTED'
'that's' acts as a link.
(Other definitions for disinterested that I've seen before include "Impartial" , "Unbiased" , "Not expecting any profit" , "Desire dentist (anag) - free from partiality" , "Feeling no concern" .)