Expert wants nice spread in return (10)
I believe the answer is:
proficient
'expert' is the definition.
(I know that expert can be written as proficient)
'nice spread in return' is the wordplay.
'spread' indicates anagramming the letters.
'in' is an insertion indicator.
'return' becomes 'profit' (I've seen this in another clue).
'nice' is an anagram of 'cien'.
'cien' going into 'profit' is 'PROFICIENT'.
'wants' is the link.
(Other definitions for proficient that I've seen before include "Competent, skilled" , "Competent, thoroughly qualified" , "having great facility" , "Showing skill" , "Well-skilled" .)