Allow discontented sweetheart to have a portion - it's excellent (7)
I believe the answer is:
awesome
'excellent' is the definition.
(I've seen this before)
'allow discontented sweetheart to have a portion' is the wordplay.
'discontented' says to hollow out the word (remove centre letters) (the word's contents are removed).
'sweetheart' becomes 'e' (the middle letter or heart of 'sweet').
'to have' means one lot of letters go next to another.
'a portion' becomes 'some' (I've seen this in another clue).
'allow' with its centre taken out is 'aw'.
'aw'+'e'+'some'='AWESOME'
'it's' is the link.
(Other definitions for awesome that I've seen before include "Dreadful; amazing" , "Daunting" , "Inspiring reverential fear" , "Generating fear and wonder" , "Inspiring reverence mixed with fear" .)