Eric and Basil upset and cross (9)
I believe the answer is:
irascible
'cross' is the definition.
(I've seen this before)
'eric and basil upset' is the wordplay.
'and' says to put letters next to each other.
'upset' indicates an anagram.
'eric' put after 'basil' is 'basileric'.
'basileric' is an anagram of 'IRASCIBLE'.
'and' is the link.
(Other definitions for irascible that I've seen before include "testy" , "Short-tempered" , "Cantankerous" , "Crabbed" , "Cross" .)